What’s Vulnerable › Vulnerabilities

CVE-2026-43383: net/tcp-md5: Fix MAC comparison to be constant-time

• Severity: critical (CVSS 9.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-08 · updated 2026-10-19
• Weakness: CWE-208

Description

In the Linux kernel, the following vulnerability has been resolved: net/tcp-md5: Fix MAC comparison to be constant-time To prevent timing attacks, MACs need to be compared in constant time. Use the appropriate helper function for this.

Affected products

• Linux kernel: from 2.6.20 before 5.10.253; from 5.11 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19; from 6.19 before 6.19.9 — fixed in 5.10.253, 6.1.167, 6.12.78, 6.18.19, 6.19.9, 6.6.130

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 6.1.167, 6.12.78, 6.18.19. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/02669e2a4d207068edce7e8b5fafd85822018ce6
• https://git.kernel.org/stable/c/345a9530756528d7ca407663d659c3c40e75c3dd
• https://git.kernel.org/stable/c/46d0d6f50dab706637f4c18a470aac20a21900d3
• https://git.kernel.org/stable/c/5d305a95130a8d08b9545e47f1e18d29d59866cb
• https://git.kernel.org/stable/c/821c8751fdeecdeecabeb11704dd33439c9e4bbc
• https://git.kernel.org/stable/c/ae3831b44f477de048287493e184fc3ff913b624
• https://git.kernel.org/stable/c/b502e97e29d791ff7a8051f29a414535739be218
• https://git.kernel.org/stable/c/ff44ec94d4fc8348600a69de0a8fa1102c23bce8

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