CyberSecBulletin
CVE-2026-64540NVD status: Analyzed

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-64540 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 255d03551f94c7bdd86c7d9181a70b21917d829f, 4359376e6238d89977a35086e47ca3b07f43e850, 8624e179fa3ce23c2fbd1a198ce30764b73f054a as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 255d03551f94c7bdd86c7d9181a70b21917d829f or 4359376e6238d89977a35086e47ca3b07f43e850 or 8624e179fa3ce23c2fbd1a198ce30764b73f054a or 573418f7ea8f859a841417eb4b915594094fd967, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 255d03551f94c7bdd86c7d9181a70b21917d829f; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 4359376e6238d89977a35086e47ca3b07f43e850; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 8624e179fa3ce23c2fbd1a198ce30764b73f054a; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 573418f7ea8f859a841417eb4b915594094fd967; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 0575599e451aff3c5329922562374a2cab25fc51; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 3ef79fa3860e644c8de7834fa7300e1c58f38862; 47ee3051c856cc2aa95d35d577a8cb37279d540f up to, but not including, 8ff7f2a6da4fccaa5cc9be7251a24e71e29fbd1a; and 1 more ranges255d03551f94c7bdd86c7d9181a70b21917d829f, 4359376e6238d89977a35086e47ca3b07f43e850, 8624e179fa3ce23c2fbd1a198ce30764b73f054a, 573418f7ea8f859a841417eb4b915594094fd967, 0575599e451aff3c5329922562374a2cab25fc51, 0a7d9c7c5f1f208c523abbb4db6aea7bc1fad3db
LinuxLinux Kernel2.6.14 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.97; 6.13 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.5; 7.25.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
AdjacentThe attacker must be on the same local network segment.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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