CyberSecBulletin
CVE-2026-64531NVD status: Analyzed

Linux: Integer Overflow or Wraparound

Published Updated By the CyberSecBulletin desk

CVE-2026-64531 is a high-severity integer overflow or wraparound vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ab855641241387db062a5e41d9ad6b8561542572, c66bd2626c2764f23764ff0f8277f44a9cfe8349, d573250d228401f707f4dbc09d11227a6215ee5f 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 ab855641241387db062a5e41d9ad6b8561542572 or c66bd2626c2764f23764ff0f8277f44a9cfe8349 or d573250d228401f707f4dbc09d11227a6215ee5f or f1efff8858403191361a01269c6fe8dd7f55a385, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.212 or 6.1.178 or 6.6.145 or 6.12.97, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux057dbc5b72e9fcac439cd561c3a539b8a0edeb92 up to, but not including, ab855641241387db062a5e41d9ad6b8561542572; 2532adbfe917c0e71dba2650ffc6efe396314c87 up to, but not including, c66bd2626c2764f23764ff0f8277f44a9cfe8349; 4b1a0ee6164c7204c68ab5a9c48c07bfe8852485 up to, but not including, d573250d228401f707f4dbc09d11227a6215ee5f; e6610f9c08b4c04cf7949c10fc246c071d00e935 up to, but not including, f1efff8858403191361a01269c6fe8dd7f55a385; a1e64addf3ff9257b45b78bc7d743781c3f41340 up to, but not including, dbd14f736be02cfe73049bd801af89becd1a0749; a1e64addf3ff9257b45b78bc7d743781c3f41340 up to, but not including, 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe; a1e64addf3ff9257b45b78bc7d743781c3f41340 up to, but not including, 3f1f755366687d051174739fb99f7d560202f60b; 6b099d285d7ed324494b6d684f377aa103856118; and 6 more rangesab855641241387db062a5e41d9ad6b8561542572, c66bd2626c2764f23764ff0f8277f44a9cfe8349, d573250d228401f707f4dbc09d11227a6215ee5f, f1efff8858403191361a01269c6fe8dd7f55a385, dbd14f736be02cfe73049bd801af89becd1a0749, 1b41cbe05b184f8861712f0806cc0c4f5d8c6dfe
LinuxLinux Kernel5.15.180 up to, but not including, 5.15.212; 6.1.132 up to, but not including, 6.1.178; 6.6.84 up to, but not including, 6.6.145; 6.12.20 up to, but not including, 6.12.97; 6.13.8 up to, but not including, 6.14; 6.14.1 up to, but not including, 6.18.40; 6.19 up to, but not including, 7.1.5; 6.14; and 1 more ranges5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.14, 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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
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
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: reject oversized nested action attrs Open vSwitch stores generated flow actions as nlattrs, whose nla_len field is u16. Commit a1e64addf3ff ("net: openvswitch: remove misbehaving actions length check") allowed the total sw_flow_actions stream to grow beyond 64 KiB, which is valid, but also removed the last guard preventing a generated nested action attribute from exceeding U16_MAX. An oversized generated container can thus be closed with a truncated nla_len. A later dump or teardown then walks a structurally different stream than the one that was validated. In particular, an oversized nested CLONE/CT action may cause subsequent bytes in the generated stream to be interpreted as independent actions. Keep the larger total-action-stream behavior, but make nested action close reject generated containers that do not fit in nla_len, and return the error through all callers. For recursive SAMPLE, CLONE, DEC_TTL, and CHECK_PKT_LEN builders, trim resource-owning action-list tails in reverse construction order before discarding failed wrappers, so resources copied into the rejected tails are released before the wrappers are removed. Most failed outer wrappers are discarded by truncating actions_len after child resources have been released. CHECK_PKT_LEN also trims its parent after branch resources are gone. SET/TUNNEL close failures unwind their known tun_dst ownership directly, and SET_TO_MASKED has no external ownership and truncates on close failure.

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

The underlying weakness: Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

How developers prevent this class of flaw

  • Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).

More Integer Overflow or Wraparound vulnerabilities (CWE-190)

Timeline

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

References

Recent Integer Overflow or Wraparound vulnerabilities

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