CVE-2026-43384 (GCVE-0-2026-43384)
Vulnerability from cvelistv5
Published
2026-05-08 14:21
Modified
2026-08-05 12:27
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0a3a809089eb1d4a0a2fd0c16b520d603988c859
Version: 0a3a809089eb1d4a0a2fd0c16b520d603988c859
Version: 0a3a809089eb1d4a0a2fd0c16b520d603988c859
Version: 0a3a809089eb1d4a0a2fd0c16b520d603988c859
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/Kconfig",
            "net/ipv4/tcp_ao.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8be6ed64966da48b6c4726918f106c18742a5125",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "a269cbdc442f8658bca35383e34b9d0b0ff95a1c",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "080b0e210088296dd50d6637c06c1db14246adfe",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            },
            {
              "lessThan": "67edfec516d30d3e62925c397be4a1e5185802fc",
              "status": "affected",
              "version": "0a3a809089eb1d4a0a2fd0c16b520d603988c859",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/Kconfig",
            "net/ipv4/tcp_ao.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.78",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.19",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tcp-ao: Fix MAC comparison to be constant-time\n\nTo prevent timing attacks, MACs need to be compared in constant\ntime.  Use the appropriate helper function for this."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable comparison is reached by inbound IPv4/IPv6 TCP packets carrying a TCP-AO option, before normal TCP processing of the segment.\nAC:L - The attacker controls the candidate MAC bytes and can send repeated chosen packets to average timing differences; no race or condition outside the attacker\u2019s control is required once a TCP-AO-protected socket is reachable.\nPR:N - The vulnerable path is the TCP-AO authentication check itself, so the attacker does not need the AO key or any local privilege before sending probes.\nUI:N - No victim user action is required; packet receipt by the configured TCP-AO endpoint is sufficient.\nS:U - The impact remains within the kernel/network endpoint and the TCP sessions protected by that endpoint, with no VM, sandbox, or separate security-authority escape.\nC:H - A successful MAC-forgery timing attack can let an unauthenticated network attacker impersonate a trusted TCP-AO peer and receive data made available to that authenticated peer.\nI:H - Forged valid TCP-AO segments can inject or alter arbitrary TCP stream/control data for protected connections, defeating the integrity guarantee TCP-AO is meant to provide.\nA:H - Forged valid TCP-AO control segments such as RST/FIN or malicious stream data can tear down or disrupt protected long-lived sessions such as routing/control-plane connections."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:42.918Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125"
        },
        {
          "url": "https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c"
        },
        {
          "url": "https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe"
        },
        {
          "url": "https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc"
        }
      ],
      "title": "net/tcp-ao: Fix MAC comparison to be constant-time",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43384",
    "datePublished": "2026-05-08T14:21:31.355Z",
    "dateReserved": "2026-05-01T14:12:56.006Z",
    "dateUpdated": "2026-08-05T12:27:42.918Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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