In the Linux kernel, the following vulnerability has been resolved: tcp: fix use-after-free of retransmit_skb_hint in tcp_send_synack() …
CVE-2026-98374 · GHSA-2q84-vc4j-mp23 · EUVD-2026-94323 · published 7 Oct 2026
How serious is it
- Severity: high, CVSS score 8.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-98374?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Linux Linux: c31b70c9968fe9c4194d1b5d06d07596a3b680de <c5b4da1f403a658c1c19766be2b426003ada419f
- Linux Linux: patch: 7.3
- Linux Linux: c31b70c9968fe9c4194d1b5d06d07596a3b680de <e3ea71cb1408a013ed4e8a757b815f1a919324bd
- Linux Linux: patch: 5.15.222
- Linux Linux: c31b70c9968fe9c4194d1b5d06d07596a3b680de <631aa4cb45099f09e9385dd786bd291c6270bfc4
- Linux Linux: patch: 6.18.55
- Linux Linux: patch: 7.2.9
- Linux Linux: patch: 6.6.158
- Linux Linux: patch: 6.1.189
- Linux Linux: patch: 0
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
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.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/fad6d429651e748365e93ca54645accc212f0018
- git.kernel.org/stable/c/c5b4da1f403a658c1c19766be2b426003ada419f
- git.kernel.org/stable/c/71d45049b0d631dfdbf3c65305f7fca676de023b
- git.kernel.org/stable/c/e3ea71cb1408a013ed4e8a757b815f1a919324bd
- git.kernel.org/stable/c/631aa4cb45099f09e9385dd786bd291c6270bfc4
- git.kernel.org/stable/c/0f87720c7e4bcab07c24888b3cf12bfe857bb90e
- git.kernel.org/stable/c/fe99bbeee5c5dbd3abc30721a8079ced59649d97
Merged from ENISA EUVD. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON