High 8.1Published Jul 19, 2026

CVE-2026-63925macsec: fix replay protection at XPN lower-PN wrap

Updated under an hour ago (Oct 28, 2026, 9:23 AM ET)

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Exploited in the last 30 days

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).

CVSS: 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Weakness (CWE): CWE-190
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from a21ecf0e033807b976967286e6c392f48ee2049f before dd7306779c6ce1238f4cdc34f3c1f2246b854457; from a21ecf0e033807b976967286e6c392f48ee2049f before d15130461df388136b62a7b0ce9f66e7e2fa9ff1; from a21ecf0e033807b976967286e6c392f48ee2049f before 23c0e230eab397d7f68be2538790ac41d3bb91fd; from a21ecf0e033807b976967286e6c392f48ee2049f before 679e13a65e68a67c8b3c0467c02ee89157ec6f0f; from a21ecf0e033807b976967286e6c392f48ee2049f before 79495a1b0944fe31ffd54b54b00211b493590d62; from a21ecf0e033807b976967286e6c392f48ee2049f before 6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652; from a21ecf0e033807b976967286e6c392f48ee2049f before d55acbe577db892b60547b6ef1c020b359331a6d; from a21ecf0e033807b976967286e6c392f48ee2049f before e68842b3356471ba56c882209f324613dac47f64	CNA record
linux linux_kernel linux:linux_kernel	from 5.7 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.93; from 6.13 before 6.18.35; from 6.19 before 7.0.12; 7.1; and 4 more ranges	NVD

References

References

https://git.kernel.org/stable/c/dd7306779c6ce1238f4cdc34f3c1f2246b854457	patch
https://git.kernel.org/stable/c/d15130461df388136b62a7b0ce9f66e7e2fa9ff1	patch
https://git.kernel.org/stable/c/23c0e230eab397d7f68be2538790ac41d3bb91fd	patch
https://git.kernel.org/stable/c/679e13a65e68a67c8b3c0467c02ee89157ec6f0f	patch
https://git.kernel.org/stable/c/79495a1b0944fe31ffd54b54b00211b493590d62	patch
https://git.kernel.org/stable/c/6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652	patch
https://git.kernel.org/stable/c/d55acbe577db892b60547b6ef1c020b359331a6d	patch
https://git.kernel.org/stable/c/e68842b3356471ba56c882209f324613dac47f64	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.