CVE-2026-43026

Medium

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation.

Package Linux Kernel
Published 2026-05-01
Last modified 2026-05-08
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions

Linux kernel versions 3.4 and later are affected. Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0 and their respective stable series.

Affected from
≥ 3.4
Fixed in
✓ 5.10.253 5.10.x ✓ 5.15.203 5.15.x ✓ 6.1.168 6.1.x ✓ 6.6.134 6.6.x ✓ 6.12.81 6.12.x ✓ 6.18.22 6.18.x ✓ 6.19.12 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43026 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-43026?

    CVE-2026-43026 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 3.4 onward and has been patched in 5.10.253, 5.15.203, 6.1.168 and others. CVE-2026-43026 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-43026?

    CVE-2026-43026 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-43026?

    Yes — CVE-2026-43026 has been patched. Fixed versions include 5.10.253, 5.15.203, 6.1.168 and others. If you are running Linux kernel 3.4 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-43026 actively exploited?

    No — CVE-2026-43026 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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