{"id":"CVE-2026-90054","title":"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 se…","summary":"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 se…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < 8eb51013b6308870479a64b4a2a018697b997849","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < 711bfd762bec05fb19bc3b17cbb157c39f4e66da","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < 3d4e005c198dc410ad568f832bffa7569c059ff8","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < 4fd2ee4ac154c204d95d8db72221446dac5af9b8","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < ebe55406404f3cb28e36d2b668e2c6c05026ec29","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < b8f08a94b2a4addc39249dcf9c792e786108621b","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < 47eb90299e6882d6445672530dd7c51ac33ebdbd","Linux >= 10d3be569243def8d92ac3722395ef5a59c504e6 < ce2b807f42ed5e55567b8864ab72963f90779270","Linux 4.7"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:16:53.873","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90054","references":[{"url":"https://git.kernel.org/stable/c/3d4e005c198dc410ad568f832bffa7569c059ff8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/47eb90299e6882d6445672530dd7c51ac33ebdbd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4fd2ee4ac154c204d95d8db72221446dac5af9b8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/711bfd762bec05fb19bc3b17cbb157c39f4e66da","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8eb51013b6308870479a64b4a2a018697b997849","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b8f08a94b2a4addc39249dcf9c792e786108621b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce2b807f42ed5e55567b8864ab72963f90779270","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ebe55406404f3cb28e36d2b668e2c6c05026ec29","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-17T16:21:47.903Z","epss":0.0022,"epssPercentile":0.11068,"slug":"CVE-2026-90054","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}