CVE Catalog

CVE-2026-63925

HighCVSS 8.1
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.34%

27th percentile - higher than 27% of all known CVEs

Summary

In the Linux kernel's macsec module, a vulnerability bypasses replay protection at XPN lower-PN wrap. When PN reaches 0xFFFFFFFF, incrementing overflows to 0, failing to update next_pn_halves, allowing an attacker to replay a captured frame indefinitely.

Risk Assessment

The organization is exposed to replay attacks on MACsec XPN associations, potentially compromising data integrity and confidentiality.

Recommendation

Apply the Linux kernel patch addressing this vulnerability immediately and update to a kernel version containing the fix.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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).

Vulnerability data from NVD (NIST) · CISA KEV · EPSS