CyberSecBulletin
CVE-2026-64380NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-64380 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 171605aed68380c2fa75dff9b3a1ed427c50065b, 4213c1208978483021d7d125c131de3985d38f61, 96e889bc1e759c83f25093e8c2f3da31b4973f30 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 0.44% 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 171605aed68380c2fa75dff9b3a1ed427c50065b or 4213c1208978483021d7d125c131de3985d38f61 or 96e889bc1e759c83f25093e8c2f3da31b4973f30 or 0de5b8e76847f5de26f364a82c6602c4881c30da, 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.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 171605aed68380c2fa75dff9b3a1ed427c50065b; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 4213c1208978483021d7d125c131de3985d38f61; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 96e889bc1e759c83f25093e8c2f3da31b4973f30; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 0de5b8e76847f5de26f364a82c6602c4881c30da; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 427eb7eb46425fec845a43e861f3d6e2899cae59; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 86c5d470f5d42e61123b2f4b4f0b91f4eee5b980; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 46a84715a015cb48e1b9c219dc88c03d8a541ea4; 349e13ad30b45998bb9937cfe0b32be6f951976d up to, but not including, 7ad2bcf2441430bb2e918fb3ef9a90d775a6e422; and 1 more ranges171605aed68380c2fa75dff9b3a1ed427c50065b, 4213c1208978483021d7d125c131de3985d38f61, 96e889bc1e759c83f25093e8c2f3da31b4973f30, 0de5b8e76847f5de26f364a82c6602c4881c30da, 427eb7eb46425fec845a43e861f3d6e2899cae59, 86c5d470f5d42e61123b2f4b4f0b91f4eee5b980
LinuxLinux Kernel5.7 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, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 7.25.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39

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
NetworkCan be exploited remotely over a network, including the internet.
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
LowSome restricted data can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: smb: client: harden POSIX SID length parsing posix_info_sid_size() reads sid[1] to obtain the subauthority count, but its existing boundary check still accepts buffers with only one remaining byte. Require two bytes before reading sid[1] so all client paths that reuse the helper reject truncated POSIX SIDs safely.

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: yes, 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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