CVE-2026-63925macsec: fix replay protection at XPN lower-PN wrap
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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)
- Not given
- 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
- Awaiting Analysis
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
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 |
References
- https://git.kernel.org/stable/c/dd7306779c6ce1238f4cdc34f3c1f2246b854457
- https://git.kernel.org/stable/c/d15130461df388136b62a7b0ce9f66e7e2fa9ff1
- https://git.kernel.org/stable/c/23c0e230eab397d7f68be2538790ac41d3bb91fd
- https://git.kernel.org/stable/c/679e13a65e68a67c8b3c0467c02ee89157ec6f0f
- https://git.kernel.org/stable/c/79495a1b0944fe31ffd54b54b00211b493590d62
- https://git.kernel.org/stable/c/6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652
- https://git.kernel.org/stable/c/d55acbe577db892b60547b6ef1c020b359331a6d
- https://git.kernel.org/stable/c/e68842b3356471ba56c882209f324613dac47f64
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.