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tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack() When tcp_send_synack() replaces the cloned SYN skb at the head of the retransmit queue with a copy, it frees the original with tcp_rtx_queue_unlink_and_free() and only repairs tp->highest_sack. tp->retransmit_skb_hint keeps pointing at the freed skbuff_fclone_cache object. The dangling hint is read in tcp_verify_retransmit_hint() and used as the root of the rbtree walk in tcp_xmit_retransmit_queue(). An unprivileged TFO client (sendmsg(MSG_FASTOPEN)) can arm the hint with an attacker-supplied ICMP fragmentation-needed message, after which a simultaneous open frees the armed SYN skb: BUG: KASAN: slab-use-after-free in tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316) Read of size 4 at addr ffff88800604d928 by task swapper/1/0 Call Trace: tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316) tcp_simple_retransmit (net/ipv4/tcp_input.c:3158) tcp_v4_err (net/ipv4/tcp_ipv4.c:587) Sync the hint to the copy.

Announced Source revision 1
Original source ↗

CVE-2026-98374

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-2026-98374

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": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "fad6d429651e748365e93ca54645accc212f0018",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "c5b4da1f403a658c1c19766be2b426003ada419f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "71d45049b0d631dfdbf3c65305f7fca676de023b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "e3ea71cb1408a013ed4e8a757b815f1a919324bd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "631aa4cb45099f09e9385dd786bd291c6270bfc4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "0f87720c7e4bcab07c24888b3cf12bfe857bb90e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c31b70c9968fe9c4194d1b5d06d07596a3b680de",
        "lessThan": "fe99bbeee5c5dbd3abc30721a8079ced59649d97",
        "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": "5.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.11",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.15.222",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.112",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.55",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.9",
        "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-2026-98374

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#55583 · Revision 1
Added to Heist Feed
Publisher date
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