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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-90054

tcp: fix corruption of urgent data on multi-segment retransmit

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: tcp: fix corruption of urgent data on multi-segment retransmit On the normal xmit path, while in urgent mode we refuse to build a multi-segment TSO packet, so every segment gets its own urg_ptr: /* tcp_write_xmit() */ limit = mss_now; if (tso_segs > 1 && !tcp_urg_mode(tp)) limit = tcp_mss_split_point(...); The retransmit path has no such guard. __tcp_retransmit_skb() builds a segs > 1 skb and hands it to the GSO layer, which only advances th->seq per segment and copies urg_ptr verbatim: /* __tcp_retransmit_skb() */ len = cur_mss * segs; /* segs > 1, no urg_mode check */ ... /* tcp_gso_segment(): bumps seq only, urg_ptr is copied */ urg_ptr is an offset from the segment's own seq, so a copied value points at a different place on each segment. The receiver rebuilds the absolute urgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead of the one OOB byte: seg1 seq 1 urg_ptr 5001 -> urgent @ 5001 (ok) seg2 seq 1001 urg_ptr 5001 -> urgent @ 6001 (wrong, +MSS) seg3 seq 2001 urg_ptr 5001 -> urgent @ 7001 (wrong, +2*MSS) The real OOB byte is never pointed at, so the receiver stops splicing it out and delivers it as normal in-band data, corrupting the stream. Guard the retransmit length like the xmit path: keep segs = 1 while in urgent mode.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < 8eb51013b6308870479a64b4a2a018697b997849affected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < 711bfd762bec05fb19bc3b17cbb157c39f4e66daaffected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < 3d4e005c198dc410ad568f832bffa7569c059ff8affected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < 4fd2ee4ac154c204d95d8db72221446dac5af9b8affected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < ebe55406404f3cb28e36d2b668e2c6c05026ec29affected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < b8f08a94b2a4addc39249dcf9c792e786108621baffected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < 47eb90299e6882d6445672530dd7c51ac33ebdbdaffected
  • 10d3be569243def8d92ac3722395ef5a59c504e6 to < ce2b807f42ed5e55567b8864ab72963f90779270affected

Linux Linux

Default version status: affected

  • 4.7affected
  • 0 to < 4.7unaffected
  • 5.10.270 to ≤ 5.10.*unaffected
  • 5.15.221 to ≤ 5.15.*unaffected
  • 6.1.188 to ≤ 6.1.*unaffected
  • 6.6.157 to ≤ 6.6.*unaffected
  • 6.12.110 to ≤ 6.12.*unaffected
  • 6.18.52 to ≤ 6.18.*unaffected
  • 7.2.6 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References