CVE-2026-98374tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()
- 8.8HighCVSS base score
- 0.29%Exploitation in 30 daysEPSS · top 78% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 12 days later
· 12 days later
Published
- 17 days later
· 17 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | High8.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.29% · top 78% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.
Affected products
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < fad6d429651e748365e93ca54645accc212f0018
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < c5b4da1f403a658c1c19766be2b426003ada419f
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < 71d45049b0d631dfdbf3c65305f7fca676de023b
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < e3ea71cb1408a013ed4e8a757b815f1a919324bd
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < 631aa4cb45099f09e9385dd786bd291c6270bfc4
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < 0f87720c7e4bcab07c24888b3cf12bfe857bb90e
- affected c31b70c9968fe9c4194d1b5d06d07596a3b680de – < fe99bbeee5c5dbd3abc30721a8079ced59649d97
- affected 5.11
- unaffected < 5.11
- unaffected 5.15.222 – ≤ 5.15.*
- unaffected 6.1.189 – ≤ 6.1.*
- unaffected 6.6.158 – ≤ 6.6.*
- unaffected 6.12.112 – ≤ 6.12.*
- unaffected 6.18.55 – ≤ 6.18.*
- unaffected 7.2.9 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References7
- https://git.kernel.org/stable/c/fad6d429651e748365e93ca54645accc212f0018 (opens in a new tab)
- https://git.kernel.org/stable/c/c5b4da1f403a658c1c19766be2b426003ada419f (opens in a new tab)
- https://git.kernel.org/stable/c/71d45049b0d631dfdbf3c65305f7fca676de023b (opens in a new tab)
- https://git.kernel.org/stable/c/e3ea71cb1408a013ed4e8a757b815f1a919324bd (opens in a new tab)
- https://git.kernel.org/stable/c/631aa4cb45099f09e9385dd786bd291c6270bfc4 (opens in a new tab)
- https://git.kernel.org/stable/c/0f87720c7e4bcab07c24888b3cf12bfe857bb90e (opens in a new tab)
- https://git.kernel.org/stable/c/fe99bbeee5c5dbd3abc30721a8079ced59649d97 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-94323 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-98374)Record last updated .