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CVE-2026-43383

kernel: net/tcp-md5: Fix MAC comparison to be constant-time

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Severity

Moderate

Red Hat Product Security

4.7

CVSS 3.1

Review impact separately from score.

Published · May 8, 2026

Updated · October 29, 2026

Description

A flaw was found in the Linux kernel's TCP MD5 signature option. This vulnerability allows a remote attacker to perform timing attacks due to a non-constant-time comparison of Message Authentication Codes (MACs). By observing the time taken for MAC comparisons, an attacker could potentially infer sensitive information, which may aid in further exploitation.

Statement

Red Hat acknowledges the upstream Linux kernel correction for «net/tcp-md5» as described in COMMENT_ZERO. Fixes are delivered through standard kernel errata for supported products. Operational exposure depends on whether this subsystem or driver is active in your configuration.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 4.7
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE-208 · Observable Timing Discrepancy