CVE-2026-64540: usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup()
In the Linux kernel, the following vulnerability has been resolved:
usbnet: gl620a: fix out-of-bounds read in genelinkrxfixup()
genelinkrxfixup() splits an aggregated RX frame into its individual packets, using a per-packet length taken from device-supplied data. That length is only bounded by GLMAXPACKETLEN (1514); it is never compared against how many bytes were actually received.
A malicious GeneLink (GL620A) device can therefore send a short URB whose header claims packetcount > 1 and a first packet of up to 1514 bytes.
skbputdata(glskb, packet->packetdata, size);
then copies past the end of the receive buffer and hands the adjacent slab contents up the network stack, an out-of-bounds read that leaks kernel heap. No privilege is required: the path runs in the usbnet RX softirq as soon as the interface is up.
BUG: KASAN: slab-out-of-bounds in genelinkrxfixup (drivers/net/usb/gl620a.c:112) Read of size 1514 at addr ffff888011309708 by task ksoftirqd/0/14 Call Trace: ... asanmemcpy (mm/kasan/shadow.c:105) genelinkrxfixup (include/linux/skbuff.h:2814 drivers/net/usb/gl620a.c:112) usbnetbh (drivers/net/usb/usbnet.c:572 drivers/net/usb/usbnet.c:1589) processonework (kernel/workqueue.c:3322) bhworker (kernel/workqueue.c:3405) taskletaction (kernel/softirq.c:965) handlesoftirqs (kernel/softirq.c:622) runksoftirqd (kernel/softirq.c:1076) ...
skbpull() already verifies that the requested length fits the buffer and returns NULL otherwise. Move it ahead of the copy and check its result, so a packet that overruns the received data is rejected before it is read. Well-formed frames, whose packets are fully present, are unaffected.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1
Event History
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the severity of CVE-2026-64540?
The severity of CVE-2026-64540 is rated as high with a CVSS score of 8.1.
How do I fix CVE-2026-64540?
To fix CVE-2026-64540, ensure that your Linux kernel is updated to the latest version that addresses this vulnerability.
What issues does CVE-2026-64540 cause?
CVE-2026-64540 can lead to an out-of-bounds read, which may compromise the system's security and stability.
Which software is affected by CVE-2026-64540?
CVE-2026-64540 affects the Linux kernel, specifically the usbnet driver related to the gl620a chipset.
When was CVE-2026-64540 published?
CVE-2026-64540 was published on July 27, 2026.