CVE-2026-63925 | Vulnerability Intelligence

Stored catalog record

Source record retrieved 2026-10-28T10:25:50.449727+00:00. Scheduled imports handle updates; this page does not assert that the provider was queried just now.

Vulnerability overview

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).

Patch review priority

Assess exposure and vendor guidance

No higher-priority signal is available in the current stored evidence.

FIRST EPSS: 0.35% · percentile 28.1 · score date 2026-10-27.

EPSS estimates probability of exploitation in the next 30 days. It does not measure your exposure or prove exploitation. The elevated threshold is 10%; CISA KEV takes precedence. About FIRST EPSS ↗

Severity and scoring

CVSS score: 8.1 · HIGH
CVSS version: 3.1
CVSS vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Weaknesses: CWE-190

CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.

Known exploitation and remediation

Not listed in the CISA catalog retrieved for this record. This does not establish that exploitation has not occurred.

Verify affected versions and patch availability in the vendor advisory before making changes.

Affected products and versions

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 5.7
Before (exclusive): 5.10.259
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 5.11
Before (exclusive): 5.15.210
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 5.16
Before (exclusive): 6.1.176
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 6.2
Before (exclusive): 6.6.143
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 6.7
Before (exclusive): 6.12.93
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 6.13
Before (exclusive): 6.18.35
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
From (inclusive): 6.19
Before (exclusive): 7.0.12
cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*

These are NVD CPE applicability entries. Some products depend on configuration conditions; consult the official record to confirm applicability.

Advisories and references

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