{"id":"CVE-2026-90054","state":"PUBLISHED","title":"tcp: fix corruption of urgent data on multi-segment retransmit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix corruption of urgent data on multi-segment retransmit\n\nOn the normal xmit path, while in urgent mode we refuse to build a\nmulti-segment TSO packet, so every segment gets its own urg_ptr:\n\n\t/* tcp_write_xmit() */\n\tlimit = mss_now;\n\tif (tso_segs > 1 && !tcp_urg_mode(tp))\n\t\tlimit = tcp_mss_split_point(...);\n\nThe retransmit path has no such guard. __tcp_retransmit_skb() builds a\nsegs > 1 skb and hands it to the GSO layer, which only advances th->seq\nper segment and copies urg_ptr verbatim:\n\n\t/* __tcp_retransmit_skb() */\n\tlen = cur_mss * segs;\t\t/* segs > 1, no urg_mode check */\n\t...\n\t/* tcp_gso_segment(): bumps seq only, urg_ptr is copied */\n\nurg_ptr is an offset from the segment's own seq, so a copied value points\nat a different place on each segment. The receiver rebuilds the absolute\nurgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead\nof the one OOB byte:\n\n\tseg1  seq 1     urg_ptr 5001 -> urgent @ 5001   (ok)\n\tseg2  seq 1001  urg_ptr 5001 -> urgent @ 6001   (wrong, +MSS)\n\tseg3  seq 2001  urg_ptr 5001 -> urgent @ 7001   (wrong, +2*MSS)\n\nThe real OOB byte is never pointed at, so the receiver stops splicing it\nout and delivers it as normal in-band data, corrupting the stream.\n\nGuard the retransmit length like the xmit path: keep segs = 1 while in\nurgent mode.","publishedAt":"2026-09-17T16:05:39.632Z","updatedAt":"2026-10-19T08:57:11.615Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"8eb51013b6308870479a64b4a2a018697b997849","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"711bfd762bec05fb19bc3b17cbb157c39f4e66da","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"3d4e005c198dc410ad568f832bffa7569c059ff8","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"4fd2ee4ac154c204d95d8db72221446dac5af9b8","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"ebe55406404f3cb28e36d2b668e2c6c05026ec29","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"b8f08a94b2a4addc39249dcf9c792e786108621b","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"47eb90299e6882d6445672530dd7c51ac33ebdbd","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"ce2b807f42ed5e55567b8864ab72963f90779270","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_output.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_output.c"]}],"references":["https://git.kernel.org/stable/c/8eb51013b6308870479a64b4a2a018697b997849","https://git.kernel.org/stable/c/711bfd762bec05fb19bc3b17cbb157c39f4e66da","https://git.kernel.org/stable/c/3d4e005c198dc410ad568f832bffa7569c059ff8","https://git.kernel.org/stable/c/4fd2ee4ac154c204d95d8db72221446dac5af9b8","https://git.kernel.org/stable/c/ebe55406404f3cb28e36d2b668e2c6c05026ec29","https://git.kernel.org/stable/c/b8f08a94b2a4addc39249dcf9c792e786108621b","https://git.kernel.org/stable/c/47eb90299e6882d6445672530dd7c51ac33ebdbd","https://git.kernel.org/stable/c/ce2b807f42ed5e55567b8864ab72963f90779270"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90054.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90054","state":"PUBLISHED","datePublished":"2026-09-17T16:05:39.632Z","dateUpdated":"2026-10-19T08:57:11.615Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.783Z"},"containers":{"cna":{"title":"tcp: fix corruption of urgent data on multi-segment retransmit","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix corruption of urgent data on multi-segment retransmit\n\nOn the normal xmit path, while in urgent mode we refuse to build a\nmulti-segment TSO packet, so every segment gets its own urg_ptr:\n\n\t/* tcp_write_xmit() */\n\tlimit = mss_now;\n\tif (tso_segs > 1 && !tcp_urg_mode(tp))\n\t\tlimit = tcp_mss_split_point(...);\n\nThe retransmit path has no such guard. __tcp_retransmit_skb() builds a\nsegs > 1 skb and hands it to the GSO layer, which only advances th->seq\nper segment and copies urg_ptr verbatim:\n\n\t/* __tcp_retransmit_skb() */\n\tlen = cur_mss * segs;\t\t/* segs > 1, no urg_mode check */\n\t...\n\t/* tcp_gso_segment(): bumps seq only, urg_ptr is copied */\n\nurg_ptr is an offset from the segment's own seq, so a copied value points\nat a different place on each segment. The receiver rebuilds the absolute\nurgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead\nof the one OOB byte:\n\n\tseg1  seq 1     urg_ptr 5001 -> urgent @ 5001   (ok)\n\tseg2  seq 1001  urg_ptr 5001 -> urgent @ 6001   (wrong, +MSS)\n\tseg3  seq 2001  urg_ptr 5001 -> urgent @ 7001   (wrong, +2*MSS)\n\nThe real OOB byte is never pointed at, so the receiver stops splicing it\nout and delivers it as normal in-band data, corrupting the stream.\n\nGuard the retransmit length like the xmit path: keep segs = 1 while in\nurgent mode."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"8eb51013b6308870479a64b4a2a018697b997849","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"711bfd762bec05fb19bc3b17cbb157c39f4e66da","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"3d4e005c198dc410ad568f832bffa7569c059ff8","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"4fd2ee4ac154c204d95d8db72221446dac5af9b8","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"ebe55406404f3cb28e36d2b668e2c6c05026ec29","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"b8f08a94b2a4addc39249dcf9c792e786108621b","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"47eb90299e6882d6445672530dd7c51ac33ebdbd","versionType":"git"},{"version":"10d3be569243def8d92ac3722395ef5a59c504e6","status":"affected","lessThan":"ce2b807f42ed5e55567b8864ab72963f90779270","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_output.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.7","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_output.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8eb51013b6308870479a64b4a2a018697b997849"},{"url":"https://git.kernel.org/stable/c/711bfd762bec05fb19bc3b17cbb157c39f4e66da"},{"url":"https://git.kernel.org/stable/c/3d4e005c198dc410ad568f832bffa7569c059ff8"},{"url":"https://git.kernel.org/stable/c/4fd2ee4ac154c204d95d8db72221446dac5af9b8"},{"url":"https://git.kernel.org/stable/c/ebe55406404f3cb28e36d2b668e2c6c05026ec29"},{"url":"https://git.kernel.org/stable/c/b8f08a94b2a4addc39249dcf9c792e786108621b"},{"url":"https://git.kernel.org/stable/c/47eb90299e6882d6445672530dd7c51ac33ebdbd"},{"url":"https://git.kernel.org/stable/c/ce2b807f42ed5e55567b8864ab72963f90779270"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:57:11.615Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}