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

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-90054

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-90054

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "8eb51013b6308870479a64b4a2a018697b997849",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "711bfd762bec05fb19bc3b17cbb157c39f4e66da",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "3d4e005c198dc410ad568f832bffa7569c059ff8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "4fd2ee4ac154c204d95d8db72221446dac5af9b8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "ebe55406404f3cb28e36d2b668e2c6c05026ec29",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "b8f08a94b2a4addc39249dcf9c792e786108621b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "47eb90299e6882d6445672530dd7c51ac33ebdbd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "10d3be569243def8d92ac3722395ef5a59c504e6",
        "lessThan": "ce2b807f42ed5e55567b8864ab72963f90779270",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv4/tcp_output.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.7"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.7",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.270",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.221",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.188",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.157",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.110",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.52",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.6",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv4/tcp_output.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-90054

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#36472 · Revision 1
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