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🛡️ CVE-2026-31665 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

netfilter: nft_ct: fix use-after-free in timeout object destroy

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nft_ct: fix use-after-free in timeout object destroy

nft_ct_timeout_obj_destroy() frees the timeout object with kfree()

immediately after nf_ct_untimeout(), without waiting for an RCU grace

period. Concurrent packet processing on other CPUs may still hold

RCU-protected references to the timeout object obtained via

rcu_dereference() in nf_ct_timeout_data().

Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer

freeing until after an RCU grace period, matching the approach already

used in nfnetlink_cttimeout.c.

KASAN report:

BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0

Read of size 4 at addr ffff8881035fe19c by task exploit/80

Call Trace:

nf_conntrack_tcp_packet+0x1381/0x29d0

nf_conntrack_in+0x612/0x8b0

nf_hook_slow+0x70/0x100

__ip_local_out+0x1b2/0x210

tcp_sendmsg_locked+0x722/0x1580

__sys_sendto+0x2d8/0x320

Allocated by task 75:

nft_ct_timeout_obj_init+0xf6/0x290

nft_obj_init+0x107/0x1b0

nf_tables_newobj+0x680/0x9c0

nfnetlink_rcv_batch+0xc29/0xe00

Freed by task 26:

nft_obj_destroy+0x3f/0xa0

nf_tables_trans_destroy_work+0x51c/0x5c0

process_one_work+0x2c4/0x5a0

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2026-31665 is recorded against 2 packages.

  • kernel (from 6.19.0 up to 6.19.13)
  • linux-kernel

Timeline and source

Published on 24 April 2026 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

cert-portal.siemens.com (Web)
cert-portal.siemens.com (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2026-31665 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-04-24
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.19.0 6.19.13
linux-kernel — —

References

Similar Threats

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