CVE-2023-53619

netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

State: Published
Severity: 7.8 High
Published: Oct 7, 2025
Updated: Oct 15, 2026
Reserved: Oct 7, 2025

Description

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

netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

If nf_conntrack_init_start() fails (for example due to a register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini() clean-up path frees the nf_ct_helper_hash map.

When built with NF_CONNTRACK=y, further netfilter modules (e.g: netfilter_conntrack_ftp) can still be loaded and call nf_conntrack_helpers_register(), independently of whether nf_conntrack initialized correctly. This accesses the nf_ct_helper_hash dangling pointer and causes a uaf, possibly leading to random memory corruption.

This patch guards nf_conntrack_helper_register() from accessing a freed or uninitialized nf_ct_helper_hash pointer and fixes possible uses-after-free when loading a conntrack module.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	12f7a505331e6b2754684b509f2ac8f0011ce644 to before 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 00716f25f9697d02a0d9bd622575c7c7321ba3d0Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 61c7a5256543ae7d24cd9d21853d514c8632e1e9Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 8289d422f5e484efe4a565fe18e862ecd621c175Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 05561f822f27b9fa88fa5504ddec34bf38833034Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7Affected 12f7a505331e6b2754684b509f2ac8f0011ce644 to before 6eef7a2b933885a17679eb8ed0796ddf0ee5309bAffected
LinuxLinux	3.6Affected before 3.6Not affected 4.14.322 through 4.14.Not affected 4.19.291 through 4.19.Not affected 5.4.251 through 5.4.Not affected 5.10.188 through 5.10.Not affected 5.15.121 through 5.15.Not affected 6.1.39 through 6.1.Not affected 6.4.4 through 6.4.*Not affected 6.5 and laterNot affected

Product

Versions

LinuxLinux

12f7a505331e6b2754684b509f2ac8f0011ce644 to before 4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 00716f25f9697d02a0d9bd622575c7c7321ba3d0Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 61c7a5256543ae7d24cd9d21853d514c8632e1e9Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 8289d422f5e484efe4a565fe18e862ecd621c175Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 05561f822f27b9fa88fa5504ddec34bf38833034Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7Affected
12f7a505331e6b2754684b509f2ac8f0011ce644 to before 6eef7a2b933885a17679eb8ed0796ddf0ee5309bAffected

LinuxLinux

3.6Affected
before 3.6Not affected
4.14.322 through 4.14.*Not affected
4.19.291 through 4.19.*Not affected
5.4.251 through 5.4.*Not affected
5.10.188 through 5.10.*Not affected
5.15.121 through 5.15.*Not affected
6.1.39 through 6.1.*Not affected
6.4.4 through 6.4.*Not affected
6.5 and laterNot affected

References

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