CVE-2026-43383
kernel: net/tcp-md5: Fix MAC comparison to be constant-time
Severity
ModerateRed Hat Product Security
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 · 4.7CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE-208 · Observable Timing Discrepancy