In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

In rxrpcpreparse(), there are two paths for parsing key payloads: the XDR path (for large payloads) and the non-XDR path (for payloads <= 28 bytes). While the XDR path (rxrpcpreparsexdrrxkad()) correctly validates the ticket length against AFSTOKENRKTIXMAX, the non-XDR path fails to do so.

This allows an unprivileged user to provide a very large ticket length. When this key is later read via rxrpcread(), the total token size (toksize) calculation results in a value that exceeds AFSTOKENLENGTHMAX, triggering a WARNON().

[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpcread+0x109/0x5c0 [rxrpc]

Fix this by adding a check in the non-XDR parsing path of rxrpcpreparse() to ensure the ticket length does not exceed AFSTOKENRKTIXMAX, bringing it into parity with the XDR parsing logic.

In the Linux kernel, the following vulnerability has been resolved:

xen/privcmd: fix double free via VMA splitting

privcmdvmops defines .close (privcmdclose), but neither .maysplit nor .open. When userspace does a partial munmap() on a privcmd mapping, the kernel splits the VMA via splitvma(). Since maysplit is NULL, the split is allowed. vmareadup() copies vmprivatedata (a pages array allocated in allocemptypages()) into the new VMA without any fixup, because there is no .open callback.

Both VMAs now point to the same pages array. When the unmapped portion is closed, privcmdclose() calls: - xenunmapdomaingfnrange() - xenfreeunpopulatedpages() - kvfree(pages)

The surviving VMA still holds the dangling pointer. When it is later destroyed, the same sequence runs again, which leads to a double free.

Fix this issue by adding a .maysplit callback denying the VMA split.

This is XSA-487 / CVE-2026-31787

In the Linux kernel, the following vulnerability has been resolved:

Buffer overflow in drivers/xen/sys-hypervisor.c

The build id returned by HYPERVISORxenversion(XENVERbuildid) is neither NUL terminated nor a string.

The first causes a buffer overflow as sprintf in buildidshow will read and copy till it finds a NUL.

00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P| 00000010 b9 a8 01 42 6f 2e 32 |...Bo.2| 00000017

So use a memcpy instead of sprintf to have the correct value:

00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P| 00000010 b9 a8 01 42 |...B| 00000014

(the above have a hack to embed a zero inside and check it's returned correctly).

This is XSA-485 / CVE-2026-31786

In the Linux kernel, the following vulnerability has been resolved:

writeback: Fix use after free in inodeswitchwbsworkfn()

inodeswitchwbsworkfn() has a loop like:

wbget(newwb); while (1) { list = llistdelall(&newwb->switchwbsctxs); / Nothing to do? / if (!list) break; ... process the items ... }

Now adding of items to the list looks like:

wbqueueisw() if (llistadd(&isw->list, &wb->switchwbsctxs)) queuework(iswwq, &wb->switchwork);

Because inodeswitchwbsworkfn() loops when processing isw items, it can happen that wb->switchwork is pending while wb->switchwbsctxs is empty. This is a problem because in that case wb can get freed (no isw items -> no wb reference) while the work is still pending causing use-after-free issues.

We cannot just fix this by cancelling work when freeing wb because that could still trigger problematic 0 -> 1 transitions on wb refcount due to wbget() in inodeswitchwbsworkfn(). It could be all handled with more careful code but that seems unnecessarily complex so let's avoid that until it is proven that the looping actually brings practical benefit. Just remove the loop from inodeswitchwbsworkfn() instead. That way when wbqueueisw() queues work, we are guaranteed we have added the first item to wb->switchwbsctxs and nobody is going to remove it (and drop the wb reference it holds) until the queued work runs.

In the Linux kernel, the following vulnerability has been resolved:

ALSA: caiaq: take a reference on the USB device in createcard()

The caiaq driver stores a pointer to the parent USB device in cdev->chip.dev but never takes a reference on it. The card's privatefree callback, sndusbcaiaqcardfree(), can run asynchronously via sndcardfreewhenclosed() after the USB device has already been disconnected and freed, so any access to cdev->chip.dev in that path dereferences a freed usbdevice.

On top of the refcounting issue, the current cardfree implementation calls usbresetdevice(cdev->chip.dev). A reset in a free callback is inappropriate: the device is going away, the call takes the device lock in a teardown context, and the reset races with the disconnect path that the callback is already cleaning up after.

Take a reference on the USB device in createcard() with usbgetdev(), drop it with usbputdev() in the free callback, and remove the usbresetdevice() call.

crypto: ccp: Don't attempt to copy ID to userspace if PSP command failed

crypto: ccp: Don't attempt to copy CSR to userspace if PSP command failed

fuse: reject oversized dirents in page cache

In the Linux kernel, the following vulnerability has been resolved:

net/packet: fix TOCTOU race on mmap'd vnethdr in tpacketsnd()

In tpacketsnd(), when PACKETVNETHDR is enabled, vnethdr points directly into the mmap'd TX ring buffer shared with userspace. The kernel validates the header via packetsndvnetparse() but then re-reads all fields later in virtionethdrtoskb(). A concurrent userspace thread can modify the vnethdr fields between validation and use, bypassing all safety checks.

The non-TPACKET path (packetsnd()) already correctly copies vnethdr to a stack-local variable. All other vnethdr consumers in the kernel (tun.c, tap.c, virtionet.c) also use stack copies. The TPACKET TX path is the only caller of virtionethdrtoskb() that reads directly from user-controlled shared memory.

Fix this by copying vnethdr from the mmap'd ring buffer to a stack-local variable before validation and use, consistent with the approach used in packetsnd() and all other callers.

In the Linux kernel, the following vulnerability has been resolved:

USB: serial: ioti: fix heap overflow in getmanufinfo()

getmanufinfo() reads le16tocpu(romdesc->Size) bytes from the device I2C EEPROM into a buffer allocated with kmallocobj(), which is sizeof(struct edgetimanufdescriptor) = 10 bytes.

The Size field comes from the device and is only validated (in checki2cimage()) to make sure the descriptor fits within TIMAXI2CSIZE (16384 bytes), not against the destination buffer size. A malicious USB device can therefore set Size to any value up to 16377, causing a heap overflow of up to 16367 bytes when plugged into a host running this driver.

validcsum() is called after readrom() and also iterates buffer[0..Size-1], compounding the out-of-bounds access.

Fix by rejecting descriptors with unexpected length before calling readrom().

[ johan: amend commit message; also check for short descriptors ]

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nfqueue: hold bridge skb->dev while queued

brpassframeup() rewrites skb->dev from the ingress port to the bridge master before queueing bridge LOCALIN packets. NFQUEUE only holds references on state.in/out and bridge physdevs, so a queued bridge packet can retain a freed bridge master in skb->dev until reinjection.

When the verdict is reinjected later, brnetifreceiveskb() re-enters the receive path with skb->dev still pointing at the freed bridge master, triggering a use-after-free.

Store skb->dev in the queue entry, hold a reference on it for the queue lifetime, and use the saved device when dropping queued packets during NETDEVDOWN handling.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftfib: fix stale stack leak via the OIFNAME register

For NFTFIBRESULTOIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTNLOCAL and oif-mismatch paths nftfib{4,6}eval() only writes one register via "dest = 0". The remaining three registers are left as whatever was on the stack in nftdochain()'s struct nftregs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace.

The NFTAFIBFPRESENT existence check has the same shape: it is only meaningful for NFTFIBRESULTOIF, yet it was accepted for any result type while the eval stores a single byte via nftregstore8(), leaving the rest of the declared span stale.

Fix both:

- replace the bare "dest = 0" in the eval with nftfibstoreresult(), which strscpypad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and

- restrict NFTAFIBFPRESENT to NFTFIBRESULTOIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes.

In the Linux kernel, the following vulnerability has been resolved:

ipv6: mcast: Fix use-after-free when processing MLD queries

When processing an MLD query, a pointer to the multicast group address is retrieved when initially parsing the packet. This pointer is later dereferenced without being reloaded despite the fact that the skb header might have been reallocated following the pskbmaypull() calls, leading to a use-after-free [1].

Fix by copying the multicast group address when the packet is initially parsed.

[1] BUG: KASAN: slab-use-after-free in mldquerywork (net/ipv6/mcast.c:1512) Read of size 8 at addr ffff8881154b8e90 by task kworker/4:1/118

Workqueue: mld mldquerywork Call Trace: <TASK> dumpstacklvl (lib/dumpstack.c:94 lib/dumpstack.c:120) printaddressdescription.constprop.0 (mm/kasan/report.c:378) printreport (mm/kasan/report.c:482) kasanreport (mm/kasan/report.c:595) mldquerywork (net/ipv6/mcast.c:1512) mldquerywork (net/ipv6/mcast.c:1563) processonework (kernel/workqueue.c:3314) workerthread (kernel/workqueue.c:3397 kernel/workqueue.c:3478) kthread (kernel/kthread.c:436) retfromfork (arch/x86/kernel/process.c:158) retfromforkasm (arch/x86/entry/entry64.S:245) </TASK>

[...]

Freed by task 118: kasansavestack (mm/kasan/common.c:57) kasansavetrack (mm/kasan/common.c:78) kasansavefreeinfo (mm/kasan/generic.c:584) kasanslabfree (mm/kasan/common.c:253 mm/kasan/common.c:285) kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6251 mm/slub.c:6566) pskbexpandhead (net/core/skbuff.c:2335) pskbpulltail (net/core/skbuff.c:2878 (discriminator 4)) mldquerywork (net/ipv6/mcast.c:1495 (discriminator 1)) mldquerywork (net/ipv6/mcast.c:1563) processonework (kernel/workqueue.c:3314) workerthread (kernel/workqueue.c:3397 kernel/workqueue.c:3478) kthread (kernel/kthread.c:436) retfromfork (arch/x86/kernel/process.c:158) retfromforkasm (arch/x86/entry/entry64.S:245)

In the Linux kernel, the following vulnerability has been resolved:

In the Linux kernel, the following vulnerability has been resolved:

x86/CPU/AMD: Prevent improper isolation of shared resources in Zen2's op cache

Make sure resources are not improperly shared in the op cache and cause instruction corruption this way.

In the Linux kernel, the following vulnerability has been resolved:

net: guard timestamp cmsgs to real error queue skbs

skbiserrqueue() treats PACKETOUTGOING as the sole marker for an skb from skerrorqueue. That assumption is not true for AFPACKET sockets: outgoing packet taps are also delivered to packet sockets with skb->pkttype == PACKETOUTGOING, but their skb->cb is owned by AFPACKET instead of struct sockexterrskb.

If such an skb is received with timestamping enabled, the generic timestamp cmsg path can read AFPACKET control-buffer state as sockexterrskb::optstats. With SORXQOVFL enabled, the packet drop counter overlaps optstats. An odd drop count makes the path emit SCMTIMESTAMPINGOPTSTATS with skb->len and skb->data. For non-linear skbs this copies past the linear head and can trigger hardened usercopy or disclose adjacent heap contents.

Keep skbiserrqueue() local to net/socket.c, but make it verify that the PACKETOUTGOING marker is paired with the sockrmemfree destructor installed by sockqueueerrskb(). AFPACKET receive skbs use normal receive ownership and no longer pass as error-queue skbs, while legitimate skerrorqueue entries keep the PACKETOUTGOING marker and sockrmemfree ownership.

In the Linux kernel, the following vulnerability has been resolved:

net: skbuff: fix missing zerocopy reference in pskbcarve helpers

pskbcarveinsideheader() and pskbcarveinsidenonlinear() both copy the old skbsharedinfo header into a new buffer via memcpy(), which includes the destructorarg pointer (uarg) for MSGZEROCOPY skbs. Neither function calls netzcopyget() for the new shinfo, creating an unaccounted holder: every skbsharedinfo with destructorarg set will call skbzcopyclear() once when freed, but the corresponding netzcopyget() was never called for the new copy. Repeated calls drive uarg->refcnt to zero prematurely, freeing ubufinfomsgzc while TX skbs still hold live destructorarg pointers.

KASAN reports use-after-free on a freed ubufinfomsgzc:

BUG: KASAN: slab-use-after-free in skbreleasedata+0x77b/0x810 Read of size 8 at addr ffff88801574d3e8 by task poc/220

Call Trace: skbreleasedata+0x77b/0x810 kfreeskblistreason+0x13e/0x610 skbreleasedata+0x4cd/0x810 skskbreasondrop+0xf3/0x340 skbqueuepurgereason+0x282/0x440 rdstcpincfree+0x1e/0x30 rdsrecvmsg+0x354/0x1780 sysrecvmsg+0xdf/0x180

Allocated by task 219: msgzerocopyrealloc+0x157/0x7b0 tcpsendmsglocked+0x2892/0x3ba0

Freed by task 219: iprecverror+0x74a/0xb10 tcprecvmsg+0x475/0x530

The skb consuming the late access still referenced the same uarg via shinfo->destructorarg copied by pskbcarveinsidenonlinear() without a refcount bump. This has been verified to be reliably exploitable: a working proof-of-concept achieves full root privilege escalation from an unprivileged local user on a default kernel configuration.

The fix follows the pattern of pskbexpandhead() which has the same memcpy/cloned structure. For pskbcarveinsideheader(), netzcopyget() is placed after skborphanfrags() succeeds, so the orphan error path needs no cleanup. For pskbcarveinsidenonlinear(), netzcopyget() is placed after all failure points and just before skbreleasedata(), so no error path needs cleanup at all -- matching pskbexpandhead() more closely and avoiding the need for a balancing netzcopyput().

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftexthdr: fix register tracking for FPRESENT flag

nftexthdrinit() passes user-controlled priv->len to nftparseregisterstore(), which marks that many bytes in the register bitmap as initialized. However, when NFTEXTHDRFPRESENT is set, the eval paths write only 1 byte (nftregstore8) or 4 bytes (dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nftregs.

Bail out if userspace requests too much data when FPRESENT is set.

exit: prevent preemption of oopsing TASKDEAD task

bpf: Free reuseport cBPF prog after RCU grace period.

In the Linux kernel, the following vulnerability has been resolved:

signal: clear JOBCTLPENDINGMASK for caller in zapotherthreads()

When a multi-threaded process receives a stop signal (e.g., SIGSTOP), dosignalstop() sets JOBCTLSTOPPENDING and JOBCTLSTOPCONSUME on all threads and sets signal->groupstopcount to the number of threads. If one of the threads concurrently calls execve(), dethread() invokes zapotherthreads() to kill all other threads. zapotherthreads() aborts the pending group stop by resetting signal->groupstopcount to 0 and clears the JOBCTLPENDINGMASK for all other threads. However, it fails to clear the job control flags for the calling thread.

When execve() completes, the calling thread returns to user mode and checks for pending signals. Seeing the stale JOBCTLSTOPPENDING flag, it calls dosignalstop(), which invokes taskparticipategroupstop(). Since JOBCTLSTOPCONSUME is still set, it attempts to decrement the already-zero signal->groupstopcount, triggering a warning:

sig->groupstopcount == 0 WARNING: CPU: 1 PID: 6475 at kernel/signal.c:373 taskparticipategroupstop+0x215/0x2d0 Call Trace: <TASK> dosignalstop+0x3be/0x5c0 kernel/signal.c:2619 getsignal+0xa8c/0x1330 kernel/signal.c:2884 archdosignalorrestart+0xbc/0x840 arch/x86/kernel/signal.c:337 exittousermodeloop+0x8c/0x4d0 kernel/entry/common.c:98 dosyscall64+0x33e/0xf80 arch/x86/entry/syscall64.c:100 entrySYSCALL64afterhwframe+0x77/0x7f </TASK>

Fix this race condition by clearing the JOBCTLPENDINGMASK for the calling thread in zapotherthreads(), ensuring it does not retain any stale job control state after the thread group is destroyed. This aligns with other functions that tear down a thread group and abort group stops, such as zapprocess() and completesignal(), which correctly clear these flags for all threads including the current one.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftct: fix missing expect put in obj eval

nftctexpectobjeval() allocates an expectation and may call nfctexpectrelated(), but never drops its local reference.

Add nfctexpectput(exp) before return to balance allocation.

In the Linux kernel, the following vulnerability has been resolved:

ipv6: xfrm6: release dst on error in xfrm6rcvencap()

xfrm6rcvencap() performs an IPv6 route lookup when the skb does not already have a dst attached. ip6routeinputlookup() returns a referenced dst entry even when the lookup resolves to an error route.

If dst->error is set, xfrm6rcvencap() drops the skb without attaching the dst to the skb and without releasing the reference returned by the lookup. Repeated packets hitting this path therefore leak dst entries.

Release the dst before jumping to the drop path.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nflog: validate MAC header was set before dumping it

The fallback path of dumpmacheader() guards the MAC header access only with "skb->macheader != skb->networkheader", without checking skbmacheaderwasset(). When the MAC header is unset, macheader is 0xffff, so the test passes and skbmacheader(skb) returns skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads dev->hardheaderlen bytes out of bounds into the kernel log.

This is reachable via the netdev logger: nflogunknownpacket() calls dumpmacheader() unconditionally, and an skb sent through AFPACKET with PACKETQDISCBYPASS reaches the egress hook with macheader still unset (devqueuexmit(), which would reset it, is bypassed).

Add the skbmacheaderwasset() check the ARPHRDETHER path already uses, and replace the open-coded MAC header length test with skbmacheaderlen(). Only skbs with an unset MAC header are affected; valid ones are dumped as before.

BUG: KASAN: slab-out-of-bounds in dumpmacheader (net/netfilter/nflogsyslog.c:831) Read of size 1 at addr ffff88800ea49d3f by task exploit/148 Call Trace: kasanreport (mm/kasan/report.c:595) dumpmacheader (net/netfilter/nflogsyslog.c:831) nflognetdevpacket (net/netfilter/nflogsyslog.c:938 net/netfilter/nflogsyslog.c:963) nflogpacket (net/netfilter/nflog.c:260) nftlogeval (net/netfilter/nftlog.c:60) nftdochain (net/netfilter/nftablescore.c:285) nftdochainnetdev (net/netfilter/nftchainfilter.c:307) nfhookslow (net/netfilter/core.c:619) nfhookdirectegress (net/packet/afpacket.c:257) packetxmit (net/packet/afpacket.c:280) packetsendmsg (net/packet/afpacket.c:3114) syssendto (net/socket.c:2265)

In the Linux kernel, the following vulnerability has been resolved:

ipv4: restrict IPOPTSSRR and IPOPTLSRR options

This patch restricts setting Loose Source and Record Route (LSRR) and Strict Source and Record Route (SSRR) IP options to users with CAPNETRAW capability.

This prevents unprivileged applications from forcing packets to route through attacker-controlled nodes to leak TCP ISN and possibly other protocol information.

While LSRR and SSRR are commonly filtered in many network environments, they may still be supported and forwarded along some network paths.

RFC 7126 (Recommendations on Filtering of IPv4 Packets Containing IPv4 Options) recommend to drop these options in 4.3 and 4.4.

In the Linux kernel, the following vulnerability has been resolved:

tcp: restrict SOATTACHFILTER to priv users

This patch restricts the use of SOATTACHFILTER (cBPF) on TCP sockets to users with CAPNETADMIN capability.

This blocks potential side-channel attack where an unprivileged application attaches a filter to leak TCP sequence/acknowledgment numbers.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: xtables: avoid leaking percpu counter pointers

The native and compat get-entries paths copy the fixed rule entry header from the kernelized rule blob to userspace before overwriting the entry's counter fields with a sanitized counter snapshot.

On SMP kernels, entry->counters.pcnt contains the percpu allocation address used by xtables rule counters. A caller can provide a userspace buffer that faults during the initial fixed-header copy after pcnt has been copied but before the later sanitized counter copy runs. The syscall then returns -EFAULT while leaving the raw percpu pointer in userspace.

Copy only the fixed entry prefix before counters from the kernelized rule blob, then copy the sanitized counter snapshot into the counter field. Apply this ordering to the IPv4, IPv6, and ARP native and compat get-entries implementations so a fault cannot expose the internal percpu counter pointer.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: synproxy: add mutex to guard hook reference counting

As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other.

Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY.

In the Linux kernel, the following vulnerability has been resolved:

xfrm: policy: fix use-after-free on inexact bin in xfrmpolicybyselctx()

Fix the race by pruning the bin while still holding xfrmpolicylock, before dropping it. Use xfrmpolicyinexactprunebin() directly since the lock is already held. The wrapper xfrmpolicyinexactprunebin() becomes unused and is removed.

Race:

CPU0 (XFRMMSGDELPOLICY) CPU1 (XFRMMSGNEWSPDINFO) ========================== ========================== xfrmpolicybyselctx(): spinlockbh(xfrmpolicylock) bin = xfrmpolicyinexactlookup() xfrmpolicyunlink(pol) spinunlockbh(xfrmpolicylock) xfrmpolicykill(ret) // wide window, lock not held xfrmhashrebuild(): spinlockbh(xfrmpolicylock) xfrmpolicyinexactflush(): kfreercu(bin) // bin freed spinunlockbh(xfrmpolicylock) xfrmpolicyinexactprunebin(bin) // UAF: bin is freed

In the Linux kernel, the following vulnerability has been resolved:

net: gro: don't merge zcopy skbs

skbgroreceive() can currently copy frags between the source and GRO skb, without checking the zerocopy status, and in particular the SKBFLMANAGEDFRAGREFS flag.

When SKBFLMANAGEDFRAGREFS is set, the skb doesn't hold a reference on the pages in shinfo->frags. Appending those frags to another skb's frags without fixing up the page refcount can lead to UAF.

When either the last skb in the GRO chain (the one we would append frags to) or the source skb is zerocopy, don't merge the skbs.