FKIE_CVE-2026-63925

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-20 15:16
Severity
8.1 (High) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
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).
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/23c0e230eab397d7f68be2538790ac41d3bb91fd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/679e13a65e68a67c8b3c0467c02ee89157ec6f0f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/79495a1b0944fe31ffd54b54b00211b493590d62
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d15130461df388136b62a7b0ce9f66e7e2fa9ff1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d55acbe577db892b60547b6ef1c020b359331a6d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/dd7306779c6ce1238f4cdc34f3c1f2246b854457
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e68842b3356471ba56c882209f324613dac47f64
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/macsec.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "dd7306779c6ce1238f4cdc34f3c1f2246b854457",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "d15130461df388136b62a7b0ce9f66e7e2fa9ff1",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "23c0e230eab397d7f68be2538790ac41d3bb91fd",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "679e13a65e68a67c8b3c0467c02ee89157ec6f0f",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "79495a1b0944fe31ffd54b54b00211b493590d62",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "6d00f5c7e5ff7ec4795b7f5f8ed88bd346641652",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "d55acbe577db892b60547b6ef1c020b359331a6d",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            },
            {
              "lessThan": "e68842b3356471ba56c882209f324613dac47f64",
              "status": "affected",
              "version": "a21ecf0e033807b976967286e6c392f48ee2049f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/macsec.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.7"
            },
            {
              "lessThan": "5.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "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)."
    }
  ],
  "id": "CVE-2026-63925",
  "lastModified": "2026-07-20T15:16:56.953",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.2,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-07-19T16:17:10.787",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "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"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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