{"id":"CVE-2026-23247","state":"PUBLISHED","title":"tcp: secure_seq: add back ports to TS offset","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: secure_seq: add back ports to TS offset\n\nThis reverts 28ee1b746f49 (\"secure_seq: downgrade to per-host timestamp offsets\")\n\ntcp_tw_recycle went away in 2017.\n\nZhouyan Deng reported off-path TCP source port leakage via\nSYN cookie side-channel that can be fixed in multiple ways.\n\nOne of them is to bring back TCP ports in TS offset randomization.\n\nAs a bonus, we perform a single siphash() computation\nto provide both an ISN and a TS offset.","publishedAt":"2026-03-18T10:05:09.353Z","updatedAt":"2026-10-30T12:23:52.715Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"025f532d8c5cfac77845e50daab7f478b360f2ac","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"e873e8c16b2fb743a381a9e59c108e63512301ec","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"5da5662181ef8a251e3ba564903002c2e87de452","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"eae2f14ab2efccdb7480fae7d42c4b0116ef8805","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"46e5b0d7cf55821527adea471ffe52a5afbd9caf","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"165573e41f2f66ef98940cf65f838b2cb575d9d1","versionType":"git"},{"version":"443fac9f2618b93cbc5ab068dc594530236b3a23","status":"affected","versionType":"git"},{"version":"4.10.14","status":"affected","lessThan":"4.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/secure_seq.h","include/net/tcp.h","net/core/secure_seq.c","net/ipv4/syncookies.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/syncookies.c","net/ipv6/tcp_ipv6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","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":["include/net/secure_seq.h","include/net/tcp.h","net/core/secure_seq.c","net/ipv4/syncookies.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/syncookies.c","net/ipv6/tcp_ipv6.c"]}],"references":["https://git.kernel.org/stable/c/025f532d8c5cfac77845e50daab7f478b360f2ac","https://git.kernel.org/stable/c/e873e8c16b2fb743a381a9e59c108e63512301ec","https://git.kernel.org/stable/c/5da5662181ef8a251e3ba564903002c2e87de452","https://git.kernel.org/stable/c/eae2f14ab2efccdb7480fae7d42c4b0116ef8805","https://git.kernel.org/stable/c/46e5b0d7cf55821527adea471ffe52a5afbd9caf","https://git.kernel.org/stable/c/165573e41f2f66ef98940cf65f838b2cb575d9d1"],"weaknesses":[],"ingestedAt":"2026-10-30T12:40:04.423Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23247.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23247","state":"PUBLISHED","datePublished":"2026-03-18T10:05:09.353Z","dateUpdated":"2026-10-30T12:23:52.715Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:45.989Z"},"containers":{"cna":{"title":"tcp: secure_seq: add back ports to TS offset","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: secure_seq: add back ports to TS offset\n\nThis reverts 28ee1b746f49 (\"secure_seq: downgrade to per-host timestamp offsets\")\n\ntcp_tw_recycle went away in 2017.\n\nZhouyan Deng reported off-path TCP source port leakage via\nSYN cookie side-channel that can be fixed in multiple ways.\n\nOne of them is to bring back TCP ports in TS offset randomization.\n\nAs a bonus, we perform a single siphash() computation\nto provide both an ISN and a TS offset."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"025f532d8c5cfac77845e50daab7f478b360f2ac","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"e873e8c16b2fb743a381a9e59c108e63512301ec","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"5da5662181ef8a251e3ba564903002c2e87de452","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"eae2f14ab2efccdb7480fae7d42c4b0116ef8805","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"46e5b0d7cf55821527adea471ffe52a5afbd9caf","versionType":"git"},{"version":"28ee1b746f493b7c62347d714f58fbf4f70df4f0","status":"affected","lessThan":"165573e41f2f66ef98940cf65f838b2cb575d9d1","versionType":"git"},{"version":"443fac9f2618b93cbc5ab068dc594530236b3a23","status":"affected","versionType":"git"},{"version":"4.10.14","status":"affected","lessThan":"4.11","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/secure_seq.h","include/net/tcp.h","net/core/secure_seq.c","net/ipv4/syncookies.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/syncookies.c","net/ipv6/tcp_ipv6.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.94","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","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":["include/net/secure_seq.h","include/net/tcp.h","net/core/secure_seq.c","net/ipv4/syncookies.c","net/ipv4/tcp_input.c","net/ipv4/tcp_ipv4.c","net/ipv6/syncookies.c","net/ipv6/tcp_ipv6.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/025f532d8c5cfac77845e50daab7f478b360f2ac"},{"url":"https://git.kernel.org/stable/c/e873e8c16b2fb743a381a9e59c108e63512301ec"},{"url":"https://git.kernel.org/stable/c/5da5662181ef8a251e3ba564903002c2e87de452"},{"url":"https://git.kernel.org/stable/c/eae2f14ab2efccdb7480fae7d42c4b0116ef8805"},{"url":"https://git.kernel.org/stable/c/46e5b0d7cf55821527adea471ffe52a5afbd9caf"},{"url":"https://git.kernel.org/stable/c/165573e41f2f66ef98940cf65f838b2cb575d9d1"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:23:52.715Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.12.94"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.18.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"6.19.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.11","versionEndExcluding":"7.0"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.10.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}