CVE-2026-63925
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).
Affected versions
Linux kernel versions
5.7
and later are affected. Fixed in
5.10.259,
5.15.210,
6.1.176,
6.6.143,
6.12.93,
6.18.35,
7.0.12,
7.1
and their respective stable series.
References
8 totalFrequently asked questions
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What is CVE-2026-63925?
CVE-2026-63925 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 5.7 onward and has been patched in 5.10.259, 5.15.210, 6.1.176 and others. CVE-2026-63925 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2026-63925?
Yes — CVE-2026-63925 has been patched. Fixed versions include 5.10.259, 5.15.210, 6.1.176 and others. If you are running Linux kernel 5.7 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2026-63925 actively exploited?
No — CVE-2026-63925 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.