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CVE-2026-98374

Updated on 07 Oct 2026

Severity

8.1 High severity

Details

CVSS score
8.1
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

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.

Details

Affected product:
AlmaLinux 9.2 ESU , TuxCare 9.6 ESU , TuxCare 9.8 ESU
Affected packages:
kernel @ 5.14.0 (+2 more)

Fixes

KernelCare state

Live-patch status from KernelCare for each operating system.

Operating system Status Covered kernels
AlmaLinux 9.2 ESU In Rollout
36 kernels
  • 5.14.0-284.1101.el9_2.tuxcare.7.els20
  • 5.14.0-284.1101.el9_2.tuxcare.7.els21
  • 5.14.0-284.1101.el9_2.tuxcare.7.els23
  • 5.14.0-284.1101.el9_2.tuxcare.7.els22
  • 5.14.0-284.1101.el9_2.tuxcare.7.els14
  • 5.14.0-284.1101.el9_2.tuxcare.7.els18
  • 5.14.0-284.1101.el9_2.tuxcare.7.els16
  • 5.14.0-284.1101.el9_2.tuxcare.7.els15
  • 5.14.0-284.1101.el9_2.tuxcare.7.els17
  • 5.14.0-284.1101.el9_2.tuxcare.7.els19
  • 5.14.0-284.1101.el9_2.tuxcare.7.els24
  • 5.14.0-284.1101.el9_2.tuxcare.7.els25
  • 5.14.0-284.1101.el9_2.tuxcare.7.els26
  • 5.14.0-284.1101.el9_2.tuxcare.7.els27
  • 5.14.0-284.1101.el9_2.tuxcare.7.els28
  • 5.14.0-284.1101.el9_2.tuxcare.7.els29
  • 5.14.0-284.1101.el9_2.tuxcare.7.els30
  • 5.14.0-284.1101.el9_2.tuxcare.7.els31
  • 5.14.0-284.1101.el9_2.tuxcare.7.els32
  • 5.14.0-284.1101.el9_2.tuxcare.7.els35
  • 5.14.0-284.1101.el9_2.tuxcare.7.els34
  • 5.14.0-284.1101.el9_2.tuxcare.11.els1
  • 5.14.0-284.1101.el9_2.tuxcare.11.els2
  • 5.14.0-284.1101.el9_2.tuxcare.11.els3
  • 5.14.0-284.1101.el9_2.tuxcare.11.els4
  • 5.14.0-284.1101.el9_2.tuxcare.11.els5
  • 5.14.0-284.1101.el9_2.tuxcare.11.els6
  • 5.14.0-284.1101.el9_2.tuxcare.11.els7
  • 5.14.0-284.1101.el9_2.tuxcare.11.els8
  • 5.14.0-284.1101.el9_2.tuxcare.11.els9
  • 5.14.0-284.1101.el9_2.tuxcare.11.els10
  • 5.14.0-284.1101.el9_2.tuxcare.11.els11
  • 5.14.0-284.1101.el9_2.tuxcare.11.els12
  • 5.14.0-284.1101.el9_2.tuxcare.11.els13
  • 5.14.0-284.1101.el9_2.tuxcare.11.els14
  • 5.14.0-284.1101.el9_2.tuxcare.7.els13
Debian 12 Planned —
Debian 13 Planned —