CVE-2025-40027: net/9p: fix double req put in p9_fd_cancelled

Q: What is the severity of CVE-2025-40027?

CVE-2025-40027 has a moderate severity rating due to potential crashes caused by a general protection fault.

Q: How do I fix CVE-2025-40027?

To fix CVE-2025-40027, update your Linux kernel to the latest version that includes the patch for this vulnerability.

Q: What impact does CVE-2025-40027 have on my system?

CVE-2025-40027 may lead to system instability or crashes due to improper handling of requests in the 9p filesystem.

Q: Is my system vulnerable to CVE-2025-40027?

Systems running the affected versions of the Linux kernel, particularly those using the 9p filesystem, may be vulnerable to CVE-2025-40027.

Q: When was CVE-2025-40027 disclosed?

CVE-2025-40027 was disclosed as part of multiple updates to the Linux kernel addressing various issues.

Published Oct 28, 2025

Updated

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

net/9p: fix double req put in p9fdcancelled

Syzkaller reports a KASAN issue as below:

general protection fault, probably for non-canonical address 0xfbd59c0000000021: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: maybe wild-memory-access in range [0xdead000000000108-0xdead00000000010f] CPU: 0 PID: 5083 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00037-g855bd1d7d838 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:listdel include/linux/list.h:114 [inline] RIP: 0010:listdelentry include/linux/list.h:137 [inline] RIP: 0010:listdel include/linux/list.h:148 [inline] RIP: 0010:p9fdcancelled+0xe9/0x200 net/9p/transfd.c:734

Call Trace: <TASK> p9clientflush+0x351/0x440 net/9p/client.c:614 p9clientrpc+0xb6b/0xc70 net/9p/client.c:734 p9clientversion net/9p/client.c:920 [inline] p9clientcreate+0xb51/0x1240 net/9p/client.c:1027 v9fssessioninit+0x1f0/0x18f0 fs/9p/v9fs.c:408 v9fsmount+0xba/0xcb0 fs/9p/vfssuper.c:126 legacygettree+0x108/0x220 fs/fscontext.c:632 vfsgettree+0x8e/0x300 fs/super.c:1573 donewmount fs/namespace.c:3056 [inline] pathmount+0x6a6/0x1e90 fs/namespace.c:3386 domount fs/namespace.c:3399 [inline] dosysmount fs/namespace.c:3607 [inline] sesysmount fs/namespace.c:3584 [inline] x64sysmount+0x283/0x300 fs/namespace.c:3584 dosyscallx64 arch/x86/entry/common.c:51 [inline] dosyscall64+0x35/0x80 arch/x86/entry/common.c:81 entrySYSCALL64afterhwframe+0x6e/0xd8

This happens because of a race condition between:

- The 9p client sending an invalid flush request and later cleaning it up; - The 9p client in p9readwork() canceled all pending requests.

Thread 1 Thread 2 ... p9clientcreate() ... p9fdcreate() ... p9conncreate() ... // start Thread 2 INITWORK(&m->rq, p9readwork); p9readwork() ... p9clientrpc() ... ... p9conncancel() ... spinlock(&m->reqlock); ... p9fdcancelled() ... ... spinunlock(&m->reqlock); // status rewrite p9clientcb(m->client, req, REQSTATUSERROR) // first remove listdel(&req->reqlist); ...

spinlock(&m->reqlock) ... // second remove listdel(&req->reqlist); spinunlock(&m->reqlock) ...

Commit 74d6a5d56629 ("9p/transfd: Fix concurrency del of reqlist in p9fdcancelled/p9readwork") fixes a concurrency issue in the 9p filesystem client where the reqlist could be deleted simultaneously by both p9readwork and p9fdcancelled functions, but for the case where req->status equals REQSTATUSRCVD.

Update the check for req->status in p9fdcancelled to skip processing not just received requests, but anything that is not SENT, as whatever changed the state from SENT also removed the request from its list.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

[updated the check from status == RECV || status == ERROR to status != SENT]

Affected Software

236 affected componentsFixes available

Linux Kernel

Microsoft azl3 kernel 6.6.104.2-4

Patch available

ubuntu/linux-aws*

ubuntu/linux-azure*

ubuntu/linux-lts-xenial*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-hwe*

ubuntu/linux-azure*

ubuntu/linux-gcp*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-kvm*

ubuntu/linux-oracle*

ubuntu/linux-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-aws-5.4*

ubuntu/linux-azure*

ubuntu/linux-azure-4.15*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-5.4*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-4.15*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gcp-5.4*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-5.4*

ubuntu/linux-hwe-edge*

ubuntu/linux-ibm-5.4*

ubuntu/linux-kvm*

ubuntu/linux-oem*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-oracle-5.4*

ubuntu/linux-raspi-5.4*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux*

ubuntu/linux-aws*

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.15<5.15.0-1100.107~20.04.2

5.15.0-1100.107~20.04.2

ubuntu/linux-aws-5.8*

ubuntu/linux-azure*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.15<5.15.0-1110.119~20.04.1

5.15.0-1110.119~20.04.1

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-bluefield*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.15<5.15.0-1100.109~20.04.1

5.15.0-1100.109~20.04.1

ubuntu/linux-gcp-5.8*

ubuntu/linux-gke*

ubuntu/linux-gke-5.15*

ubuntu/linux-gkeop*

ubuntu/linux-gkeop-5.15*

ubuntu/linux-hwe-5.11*

ubuntu/linux-hwe-5.13*

ubuntu/linux-hwe-5.15<5.15.0-170.180~20.04.3

5.15.0-170.180~20.04.3

ubuntu/linux-hwe-5.8*

ubuntu/linux-ibm*

ubuntu/linux-ibm-5.15<5.15.0-1094.97~20.04.1

5.15.0-1094.97~20.04.1

ubuntu/linux-intel-5.13*

ubuntu/linux-intel-iotg-5.15<5.15.0-1095.101~20.04.1

5.15.0-1095.101~20.04.1

ubuntu/linux-iot*

ubuntu/linux-kvm*

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-170.180~20.04.1

5.15.0-170.180~20.04.1

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1052.52~20.04.2

5.15.0-1052.52~20.04.2

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.15<5.15.0-1097.103~20.04.1

5.15.0-1097.103~20.04.1

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.15<5.15.0-1095.99~20.04.1

5.15.0-1095.99~20.04.1

ubuntu/linux-riscv-5.8*

ubuntu/linux-xilinx-zynqmp*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux<5.15.0-170.180

5.15.0-170.180

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1100.107

5.15.0-1100.107

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1050.53~22.04.1

6.8.0-1050.53~22.04.1

ubuntu/linux-azure<5.15.0-1109.118

5.15.0-1109.118

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1051.57~22.04.1

6.8.0-1051.57~22.04.1

ubuntu/linux-azure-fde<5.15.0-1109.118.1

5.15.0-1109.118.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-azure-fde-6.8<6.8.0-1058.65~22.04.1

6.8.0-1058.65~22.04.1

ubuntu/linux-gcp<5.15.0-1100.109

5.15.0-1100.109

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1052.55~22.04.1

6.8.0-1052.55~22.04.1

ubuntu/linux-gke<5.15.0-1096.102

5.15.0-1096.102

ubuntu/linux-gkeop<5.15.0-1083.91

5.15.0-1083.91

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-106.106~22.04.1

6.8.0-106.106~22.04.1

ubuntu/linux-ibm<5.15.0-1094.97

5.15.0-1094.97

ubuntu/linux-ibm-6.8<6.8.0-1049.49~22.04.1

6.8.0-1049.49~22.04.1

ubuntu/linux-intel-iot-realtime*

ubuntu/linux-intel-iotg<5.15.0-1095.101

5.15.0-1095.101

ubuntu/linux-kvm<5.15.0-1092.97

5.15.0-1092.97

ubuntu/linux-lowlatency<5.15.0-170.180

5.15.0-170.180

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-106.106.1~22.04.1

6.8.0-106.106.1~22.04.1

ubuntu/linux-nvidia<5.15.0-1095.96

5.15.0-1095.96

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1049.52~22.04.1

6.8.0-1049.52~22.04.1

ubuntu/linux-nvidia-tegra<5.15.0-1052.52

5.15.0-1052.52

ubuntu/linux-nvidia-tegra-igx<5.15.0-1041.41

5.15.0-1041.41

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1097.103

5.15.0-1097.103

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1047.48~22.04.1

6.8.0-1047.48~22.04.1

ubuntu/linux-raspi<5.15.0-1097.100

5.15.0-1097.100

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-106.106~22.04.1

6.8.0-106.106~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1064.68

5.15.0-1064.68

ubuntu/linux-bluefield<5.15.0-1084.86

5.15.0-1084.86

ubuntu/linux-intel-iot-realtime<5.15.0-1092.94

5.15.0-1092.94

ubuntu/linux-realtime<5.15.0-1099.108

5.15.0-1099.108

ubuntu/linux-realtime-6.8<6.8.1-1045.46~22.04.1

6.8.1-1045.46~22.04.1

ubuntu/linux-aws-fips*

ubuntu/linux-azure-fips*

ubuntu/linux-fips*

ubuntu/linux-gcp-fips*

ubuntu/linux-aws-fips<5.15.0-1100.107+fips1

5.15.0-1100.107+fips1

ubuntu/linux-azure-fips<5.15.0-1109.118+fips1

5.15.0-1109.118+fips1

ubuntu/linux-fips<5.15.0-170.180+fips1

5.15.0-170.180+fips1

ubuntu/linux-gcp-fips<5.15.0-1100.109+fips1

5.15.0-1100.109+fips1

ubuntu/linux<6.8.0-106.106

6.8.0-106.106

ubuntu/linux-aws<6.8.0-1050.53

6.8.0-1050.53

ubuntu/linux-aws-6.14*

ubuntu/linux-azure<6.8.0-1051.57

6.8.0-1051.57

ubuntu/linux-azure-6.11*

ubuntu/linux-azure-6.14*

ubuntu/linux-azure-fde<6.8.0-1058.65

6.8.0-1058.65

ubuntu/linux-azure-fde-6.14*

ubuntu/linux-azure-nvidia*

ubuntu/linux-azure-nvidia-6.14*

ubuntu/linux-gcp<6.8.0-1052.55

6.8.0-1052.55

ubuntu/linux-gcp-6.11*

ubuntu/linux-gcp-6.14*

ubuntu/linux-gke<6.8.0-1048.53

6.8.0-1048.53

ubuntu/linux-gkeop<6.8.0-1035.38

6.8.0-1035.38

ubuntu/linux-hwe-6.11*

ubuntu/linux-hwe-6.14*

ubuntu/linux-ibm<6.8.0-1049.49

6.8.0-1049.49

ubuntu/linux-lowlatency<6.8.0-106.106.1

6.8.0-106.106.1

ubuntu/linux-lowlatency-hwe-6.11*

ubuntu/linux-nvidia<6.8.0-1049.52

6.8.0-1049.52

ubuntu/linux-nvidia-6.11*

ubuntu/linux-nvidia-lowlatency<6.8.0-1049.52.1

6.8.0-1049.52.1

ubuntu/linux-nvidia-tegra<6.8.0-1020.20

6.8.0-1020.20

ubuntu/linux-oem-6.11*

ubuntu/linux-oem-6.14*

ubuntu/linux-oem-6.17<6.17.0-1006.6

6.17.0-1006.6

ubuntu/linux-oem-6.8*

ubuntu/linux-oracle<6.8.0-1047.48

6.8.0-1047.48

ubuntu/linux-oracle-6.14*

ubuntu/linux-raspi<6.8.0-1050.54

6.8.0-1050.54

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-6.14*

ubuntu/linux-xilinx<6.8.0-1028.29

6.8.0-1028.29

ubuntu/linux-bluefield<6.8.0-1017.21

6.8.0-1017.21

ubuntu/linux-raspi-realtime<6.8.0-2040.41

6.8.0-2040.41

ubuntu/linux-realtime<6.8.1-1045.46

6.8.1-1045.46

ubuntu/linux-realtime-6.14*

ubuntu/linux-aws-fips<6.8.0-1050.53+fips1

6.8.0-1050.53+fips1

ubuntu/linux-azure-fips<6.8.0-1052.58+fips1

6.8.0-1052.58+fips1

ubuntu/linux-fips<6.8.0-106.106+fips1

6.8.0-106.106+fips1

ubuntu/linux-gcp-fips<6.8.0-1052.55+fips1

6.8.0-1052.55+fips1

ubuntu/linux<6.17.0-7.7

6.17.0-7.7

ubuntu/linux-aws<6.17.0-1004.4

6.17.0-1004.4

ubuntu/linux-azure<6.17.0-1006.6

6.17.0-1006.6

ubuntu/linux-azure-fde*

ubuntu/linux-gcp<6.17.0-1004.4

6.17.0-1004.4

ubuntu/linux-oracle<6.17.0-1005.5

6.17.0-1005.5

ubuntu/linux-raspi<6.17.0-1005.5

6.17.0-1005.5

ubuntu/linux-realtime<6.17.0-1003.4

6.17.0-1003.4

ubuntu/linux-riscv<6.17.0-7.7.1

6.17.0-7.7.1

debian/linux

6.1.176-16.1.190-16.12.107-16.12.115-27.2.15-17.3.3-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1100.107~20.04.2
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Fixed in 5.15.0-1110.119~20.04.1
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Fixed in 5.15.0-1100.109~20.04.1
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Fixed in 5.15.0-170.180~20.04.3
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Fixed in 5.15.0-1094.97~20.04.1
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Fixed in 5.15.0-1095.101~20.04.1
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Fixed in 5.15.0-170.180~20.04.1
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Fixed in 5.15.0-1052.52~20.04.2
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Fixed in 5.15.0-1097.103~20.04.1
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Fixed in 5.15.0-1095.99~20.04.1
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Fixed in 5.15.0-170.180
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Fixed in 5.15.0-1100.107
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Fixed in 6.8.0-1050.53~22.04.1
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Fixed in 5.15.0-1109.118
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Fixed in 6.8.0-1051.57~22.04.1
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Fixed in 5.15.0-1109.118.1
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Fixed in 6.8.0-1058.65~22.04.1
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Fixed in 5.15.0-1100.109
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Fixed in 6.8.0-1052.55~22.04.1
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Fixed in 5.15.0-1096.102
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Fixed in 5.15.0-1083.91
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1094.97
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Fixed in 6.8.0-1049.49~22.04.1
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Fixed in 5.15.0-1095.101
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Fixed in 5.15.0-1092.97
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Fixed in 5.15.0-170.180
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Fixed in 6.8.0-106.106.1~22.04.1
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Fixed in 5.15.0-1095.96
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Fixed in 6.8.0-1049.52~22.04.1
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Fixed in 5.15.0-1052.52
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Fixed in 5.15.0-1041.41
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Fixed in 5.15.0-1097.103
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Fixed in 6.8.0-1047.48~22.04.1
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Fixed in 5.15.0-1097.100
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Fixed in 6.8.0-106.106~22.04.1
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Fixed in 5.15.0-1064.68
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Fixed in 5.15.0-1084.86
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Fixed in 5.15.0-1092.94
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Fixed in 5.15.0-1099.108
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Fixed in 6.8.1-1045.46~22.04.1
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Fixed in 5.15.0-1100.107+fips1
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Fixed in 5.15.0-1109.118+fips1
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Fixed in 5.15.0-170.180+fips1
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Fixed in 5.15.0-1100.109+fips1
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Fixed in 6.8.0-106.106
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Fixed in 6.8.0-1050.53
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Fixed in 6.8.0-1051.57
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Fixed in 6.8.0-1058.65
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Fixed in 6.8.0-1052.55
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Fixed in 6.8.0-1048.53
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Fixed in 6.8.0-1035.38
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Fixed in 6.8.0-1049.49
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Fixed in 6.8.0-106.106.1
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Fixed in 6.8.0-1049.52
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Fixed in 6.8.0-1049.52.1
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Fixed in 6.8.0-1020.20
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Fixed in 6.17.0-1006.6
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Fixed in 6.8.0-1047.48
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Fixed in 6.8.0-1050.54
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Fixed in 6.8.0-1028.29
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Fixed in 6.8.0-1017.21
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Fixed in 6.8.0-2040.41
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Fixed in 6.8.1-1045.46
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Fixed in 6.8.0-1050.53+fips1
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Fixed in 6.8.0-1052.58+fips1
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Fixed in 6.8.0-106.106+fips1
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Fixed in 6.8.0-1052.55+fips1
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Fixed in 6.17.0-7.7
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Fixed in 6.17.0-1004.4
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Fixed in 6.17.0-1006.6
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Fixed in 6.17.0-1004.4
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Fixed in 6.17.0-1005.5
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Fixed in 6.17.0-1005.5
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Fixed in 6.17.0-1003.4
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Fixed in 6.17.0-7.7.1
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Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.115-2Fixed in 7.2.15-1Fixed in 7.3.3-1
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Patch 74d6a5d56629

Event History

Oct 28, 2025

CVE Published

via MITRE·09:32 AM

Data Sourced

via MITRE·09:32 AM

DescriptionSeverity

Data Sourced

via OSV·10:15 AM

DescriptionSeverityAffected Software

Data Sourced

via NVD·10:15 AM

DescriptionSeverity

Oct 29, 2025

Data Sourced

via Microsoft·01:04 AM

DescriptionSeverityWeakness

Data Sourced

via Microsoft·01:04 AM

Affected Software

Parent advisories

This vulnerability appears in the following advisories.

DSA-6053

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

What is the severity of CVE-2025-40027?

CVE-2025-40027 has a moderate severity rating due to potential crashes caused by a general protection fault.

How do I fix CVE-2025-40027?

To fix CVE-2025-40027, update your Linux kernel to the latest version that includes the patch for this vulnerability.

What impact does CVE-2025-40027 have on my system?

CVE-2025-40027 may lead to system instability or crashes due to improper handling of requests in the 9p filesystem.

Is my system vulnerable to CVE-2025-40027?

Systems running the affected versions of the Linux kernel, particularly those using the 9p filesystem, may be vulnerable to CVE-2025-40027.

When was CVE-2025-40027 disclosed?

CVE-2025-40027 was disclosed as part of multiple updates to the Linux kernel addressing various issues.

CVE-2025-40027: net/9p: fix double req put in p9_fd_cancelled

Affected Software

Remediation

Event History

Parent advisories

Peer vulnerabilities

Frequently Asked Questions

What is the severity of CVE-2025-40027?

How do I fix CVE-2025-40027?

What impact does CVE-2025-40027 have on my system?

Is my system vulnerable to CVE-2025-40027?

When was CVE-2025-40027 disclosed?

Company

Resources

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