CVE-2026-43025

netfilter: ctnetlink: ignore explicit helper on new expectations

HIGH

7.3

CVSS Score

Published: May 1, 2026 at 02:15 PM UTC

Updated: October 19, 2026 at 08:18 PM UTC

4 products affected across 2 vendorsLinux KernelSIMATIC S7-1500 CPU 1518-4 Pn /dp MFP FirmwareSiplus S7-1500 CPU 1518-4 Pn /dp MFP Firmware

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Severity

HIGH7.3

Exploit prediction

EPSS 0.1%

SSVC

No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: ignore explicit helper on new expectations Use the existing master conntrack helper, anything else is not really supported and it just makes validation more complicated, so just ignore what helper userspace suggests for this expectation. This was uncovered when validating CTA_EXPECT_CLASS via different helper provided by userspace than the existing master conntrack helper: BUG: KASAN: slab-out-of-bounds in nf_ct_expect_related_report+0x2479/0x27c0 Read of size 4 at addr ffff8880043fe408 by task poc/102 Call Trace: nf_ct_expect_related_report+0x2479/0x27c0 ctnetlink_create_expect+0x22b/0x3b0 ctnetlink_new_expect+0x4bd/0x5c0 nfnetlink_rcv_msg+0x67a/0x950 netlink_rcv_skb+0x120/0x350 Allowing to read kernel memory bytes off the expectation boundary. CTA_EXPECT_HELP_NAME is still used to offer the helper name to userspace via netlink dump.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

3.12 ≤ v < 6.1.1686.13 ≤ v < 6.18.226.19 ≤ v < 6.19.126.2 ≤ v < 6.6.1346.7 ≤ v < 6.12.817.0 7.0 rc1 7.0 rc2 7.0 rc3 7.0 rc4 7.0 rc5 7.0 rc6bd0779370588386e4a67ba5d0b176cfded8e6a53

Vendor states this is fixed in 0f6c33697ccfac6499d0b7a4dbdec5d3a3a566cd (fixed)

Vendor states this is fixed in 187b6ec5229ea93cb04c4f6d3b52efc80f513d0d (fixed)

Vendor states this is fixed in 21a04c31db4057deec85fcd6cc63d720b38819c3 (fixed)

Vendor states this is fixed in 2ea0f35f235f70c133ad61fe05ba013753b978c6 (fixed)

Vendor states this is fixed in 917b61fa2042f11e2af4c428e43f08199586633a (fixed)

Vendor states this is fixed in e135f8e8212cbed12a03ab8dec77fa1247139897 (fixed)

Vendor states this is fixed in 3.12 (unaffected)

Vendor states this is fixed in 6.1.168 (unaffected)

Vendor states this is fixed in 6.12.81 (unaffected)

Vendor states this is fixed in 6.18.22 (unaffected)

Vendor states this is fixed in 6.19.12 (unaffected)

Vendor states this is fixed in 6.6.134 (unaffected)