CVE-2026-98374
tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack()
No known exploitation. EPSS puts it in the 5th percentile. Fixed versions are out.
What to do
Find your product and version, then upgrade to the build on the right.
- LinuxAffected: ≥ c31b70c9968fe9c4194d1b5d06d07596a3b680de, < fad6d429651e748365e93ca54645accc212f0018Upgrade to: fad6d429651e748365e93ca54645accc212f0018Affected: ≥ c31b70c9968fe9c4194d1b5d06d07596a3b680de, < c5b4da1f403a658c1c19766be2b426003ada419fUpgrade to: c5b4da1f403a658c1c19766be2b426003ada419fAffected: ≥ c31b70c9968fe9c4194d1b5d06d07596a3b680de, < 71d45049b0d631dfdbf3c65305f7fca676de023bUpgrade to: 71d45049b0d631dfdbf3c65305f7fca676de023bAffected: ≥ c31b70c9968fe9c4194d1b5d06d07596a3b680de, < e3ea71cb1408a013ed4e8a757b815f1a919324bdUpgrade to: e3ea71cb1408a013ed4e8a757b815f1a919324bd + 3 more branchesStated by: CVE record
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE 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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.2% chance of exploitation activity in the next 30 days, which ranks it in the 5th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
2 events over 0 days, from the signal feeds we watch.
- Publishedrecord updated
Affected products
Sources
References in the record
- git.kernel.org/stable/c/fad6d429651e748365e93ca54645accc212f0018
- git.kernel.org/stable/c/c5b4da1f403a658c1c19766be2b426003ada419f
- git.kernel.org/stable/c/71d45049b0d631dfdbf3c65305f7fca676de023b
And 4 more references. See all after sign-in
In the news
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