{"id":"CVE-2026-43384","state":"PUBLISHED","title":"net/tcp-ao: Fix MAC comparison to be constant-time","description":"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.","publishedAt":"2026-05-08T14:21:31.355Z","updatedAt":"2026-08-05T12:27:42.918Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"8be6ed64966da48b6c4726918f106c18742a5125","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"a269cbdc442f8658bca35383e34b9d0b0ff95a1c","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"080b0e210088296dd50d6637c06c1db14246adfe","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"67edfec516d30d3e62925c397be4a1e5185802fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/Kconfig","net/ipv4/tcp_ao.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.7","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.19","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.9","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/Kconfig","net/ipv4/tcp_ao.c"]}],"references":["https://git.kernel.org/stable/c/8be6ed64966da48b6c4726918f106c18742a5125","https://git.kernel.org/stable/c/a269cbdc442f8658bca35383e34b9d0b0ff95a1c","https://git.kernel.org/stable/c/080b0e210088296dd50d6637c06c1db14246adfe","https://git.kernel.org/stable/c/67edfec516d30d3e62925c397be4a1e5185802fc"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43384.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43384","state":"PUBLISHED","datePublished":"2026-05-08T14:21:31.355Z","dateUpdated":"2026-08-05T12:27:42.918Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.006Z"},"containers":{"cna":{"title":"net/tcp-ao: Fix MAC comparison to be constant-time","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"8be6ed64966da48b6c4726918f106c18742a5125","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"a269cbdc442f8658bca35383e34b9d0b0ff95a1c","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"080b0e210088296dd50d6637c06c1db14246adfe","versionType":"git"},{"version":"0a3a809089eb1d4a0a2fd0c16b520d603988c859","status":"affected","lessThan":"67edfec516d30d3e62925c397be4a1e5185802fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/Kconfig","net/ipv4/tcp_ao.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.7","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.19","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.9","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/Kconfig","net/ipv4/tcp_ao.c"]}],"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"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"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’s 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":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:27:42.918Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.18.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.19.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}