CVE-2026-63925 (GCVE-0-2026-63925)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-07-20 13:41
VLAI
Title
macsec: fix replay protection at XPN lower-PN wrap
Summary
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).
Severity
8.1 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < dd7306779c6ce1238f4cdc34f3c1f2246b854457 (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < d15130461df388136b62a7b0ce9f66e7e2fa9ff1 (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < 23c0e230eab397d7f68be2538790ac41d3bb91fd (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < 679e13a65e68a67c8b3c0467c02ee89157ec6f0f (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < 79495a1b0944fe31ffd54b54b00211b493590d62 (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < 6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652 (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < d55acbe577db892b60547b6ef1c020b359331a6d (git)
Affected: a21ecf0e033807b976967286e6c392f48ee2049f , < e68842b3356471ba56c882209f324613dac47f64 (git)
Create a notification for this product.
Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 5.10.259 , ≤ 5.10.* (semver)
Unaffected: 5.15.210 , ≤ 5.15.* (semver)
Unaffected: 6.1.176 , ≤ 6.1.* (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: fix replay protection at XPN lower-PN wrap\n\nIn macsec_post_decrypt(), when pn is U32_MAX, pn + 1 overflows u32 to 0\nand the first branch never fires. If next_pn_halves.lower is also in the\nupper half, pn_same_half(pn, lower) is true and the XPN else-if does not\nfire either, leaving next_pn_halves unchanged. An attacker that captures\nthe legitimate frame carrying pn == 0xFFFFFFFF on an XPN association\ncan then replay it indefinitely, since lowest_pn never rises above\nthe captured pn and macsec_decrypt() reconstructs the same IV.\n\nExtend the XPN else-if to also fire when pn + 1 wraps to 0, so receipt\nof pn == U32_MAX advances next_pn_halves to (upper + 1, 0)."
        }
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            "version": "3.1"
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63925",
    "datePublished": "2026-07-19T14:55:26.442Z",
    "dateReserved": "2026-07-19T07:54:57.021Z",
    "dateUpdated": "2026-07-20T13:41:35.092Z",
    "state": "PUBLISHED"
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An attacker that captures\\nthe legitimate frame carrying pn == 0xFFFFFFFF on an XPN association\\ncan then replay it indefinitely, since lowest_pn never rises above\\nthe captured pn and macsec_decrypt() reconstructs the same IV.\\n\\nExtend the XPN else-if to also fire when pn + 1 wraps to 0, so receipt\\nof pn == U32_MAX advances next_pn_halves to (upper + 1, 0).\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/net/macsec.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"dd7306779c6ce1238f4cdc34f3c1f2246b854457\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"d15130461df388136b62a7b0ce9f66e7e2fa9ff1\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"23c0e230eab397d7f68be2538790ac41d3bb91fd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"679e13a65e68a67c8b3c0467c02ee89157ec6f0f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"79495a1b0944fe31ffd54b54b00211b493590d62\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"d55acbe577db892b60547b6ef1c020b359331a6d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"a21ecf0e033807b976967286e6c392f48ee2049f\",\"lessThan\":\"e68842b3356471ba56c882209f324613dac47f64\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/net/macsec.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.7\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.7\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.259\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.210\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.176\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.143\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.93\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.35\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.12\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H\",\"baseScore\":8.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":5.2}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/23c0e230eab397d7f68be2538790ac41d3bb91fd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/679e13a65e68a67c8b3c0467c02ee89157ec6f0f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/79495a1b0944fe31ffd54b54b00211b493590d62\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d15130461df388136b62a7b0ce9f66e7e2fa9ff1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d55acbe577db892b60547b6ef1c020b359331a6d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/dd7306779c6ce1238f4cdc34f3c1f2246b854457\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e68842b3356471ba56c882209f324613dac47f64\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.