CyberSecBulletin
CVE-2026-63925NVD status: Analyzed

Linux: Integer Overflow or Wraparound

Published Updated By the CyberSecBulletin desk

CVE-2026-63925 is a high-severity integer overflow or wraparound 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 dd7306779c6ce1238f4cdc34f3c1f2246b854457, d15130461df388136b62a7b0ce9f66e7e2fa9ff1, 23c0e230eab397d7f68be2538790ac41d3bb91fd 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 0.35% 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 dd7306779c6ce1238f4cdc34f3c1f2246b854457 or d15130461df388136b62a7b0ce9f66e7e2fa9ff1 or 23c0e230eab397d7f68be2538790ac41d3bb91fd or 679e13a65e68a67c8b3c0467c02ee89157ec6f0f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxa21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, dd7306779c6ce1238f4cdc34f3c1f2246b854457; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, d15130461df388136b62a7b0ce9f66e7e2fa9ff1; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, 23c0e230eab397d7f68be2538790ac41d3bb91fd; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, 679e13a65e68a67c8b3c0467c02ee89157ec6f0f; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, 79495a1b0944fe31ffd54b54b00211b493590d62; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, 6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, d55acbe577db892b60547b6ef1c020b359331a6d; a21ecf0e033807b976967286e6c392f48ee2049f up to, but not including, e68842b3356471ba56c882209f324613dac47f64; and 1 more rangesdd7306779c6ce1238f4cdc34f3c1f2246b854457, d15130461df388136b62a7b0ce9f66e7e2fa9ff1, 23c0e230eab397d7f68be2538790ac41d3bb91fd, 679e13a65e68a67c8b3c0467c02ee89157ec6f0f, 79495a1b0944fe31ffd54b54b00211b493590d62, 6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652
LinuxLinux Kernel5.7 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.15.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35

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
NoneNo data is disclosed.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: macsec: fix replay protection at XPN lower-PN wrap In macsec_post_decrypt(), when pn is U32_MAX, pn + 1 overflows u32 to 0 and the first branch never fires. If next_pn_halves.lower is also in the upper half, pn_same_half(pn, lower) is true and the XPN else-if does not fire either, leaving next_pn_halves unchanged. An attacker that captures the legitimate frame carrying pn == 0xFFFFFFFF on an XPN association can then replay it indefinitely, since lowest_pn never rises above the captured pn and macsec_decrypt() reconstructs the same IV. Extend the XPN else-if to also fire when pn + 1 wraps to 0, so receipt of pn == U32_MAX advances next_pn_halves to (upper + 1, 0).

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: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Integer Overflow or Wraparound vulnerabilities

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