{"id":"CVE-2026-98374","title":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()\n\nWhen tcp_send_synack() replaces the cloned SYN skb at the head of the\nretransmit queue with a copy,…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()\n\nWhen tcp_send_synack() replaces the cloned SYN skb at the head of the\nretransmit queue with a copy,…","severity":"high","vendor":"Linux","product":"Linux","affected":["Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < fad6d429651e748365e93ca54645accc212f0018","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < c5b4da1f403a658c1c19766be2b426003ada419f","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < 71d45049b0d631dfdbf3c65305f7fca676de023b","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < e3ea71cb1408a013ed4e8a757b815f1a919324bd","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < 631aa4cb45099f09e9385dd786bd291c6270bfc4","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < 0f87720c7e4bcab07c24888b3cf12bfe857bb90e","Linux >= c31b70c9968fe9c4194d1b5d06d07596a3b680de < fe99bbeee5c5dbd3abc30721a8079ced59649d97","Linux 5.11"],"published":"2026-10-07","updated":"2026-10-07","sourceUpdated":"2026-10-07T13:17:23.023","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-98374","references":[{"url":"https://git.kernel.org/stable/c/0f87720c7e4bcab07c24888b3cf12bfe857bb90e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/631aa4cb45099f09e9385dd786bd291c6270bfc4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/71d45049b0d631dfdbf3c65305f7fca676de023b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c5b4da1f403a658c1c19766be2b426003ada419f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e3ea71cb1408a013ed4e8a757b815f1a919324bd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fad6d429651e748365e93ca54645accc212f0018","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fe99bbeee5c5dbd3abc30721a8079ced59649d97","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98374.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-98374"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2547433"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98374"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98374"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98374.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ingestedAt":"2026-10-07T13:31:04.600Z","epss":0.00293,"epssPercentile":0.21797,"cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-825"],"scores":{"cna":8.8,"vendor":7},"slug":"CVE-2026-98374","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()\n\nWhen tcp_send_synack() replaces the cloned SYN skb at the head of the\nretransmit queue with a copy, it frees the original with\ntcp_rtx_queue_unlink_and_free() and only repairs tp->highest_sack.\ntp->retransmit_skb_hint keeps pointing at the freed\nskbuff_fclone_cache object.\n\nThe dangling hint is read in tcp_verify_retransmit_hint() and used as\nthe root of the rbtree walk in tcp_xmit_retransmit_queue().  An\nunprivileged TFO client (sendmsg(MSG_FASTOPEN)) can arm the hint with\nan attacker-supplied ICMP fragmentation-needed message, after which a\nsimultaneous open frees the armed SYN skb:\n\n  BUG: KASAN: slab-use-after-free in tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)\n  Read of size 4 at addr ffff88800604d928 by task swapper/1/0\n  Call Trace:\n   tcp_mark_skb_lost (net/ipv4/tcp_input.c:1316)\n   tcp_simple_retransmit (net/ipv4/tcp_input.c:3158)\n   tcp_v4_err (net/ipv4/tcp_ipv4.c:587)\n\nSync the hint to the copy.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98374.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":228988,"id":"CVE-2026-98374","ts":1792854133082,"field":"cvss","old":null,"new":"8.8"},{"seq":228987,"id":"CVE-2026-98374","ts":1792854133082,"field":"severity","old":"none","new":"high"}]}