CVE-2026-43383 net/tcp-md5: Fix MAC comparison to be constant-time
An attacker can exploit a timing side-channel in TCP MD5 signature verification to potentially recover sensitive authentication data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43383?
CVE-2026-43383 is a critical vulnerability in Linux kernel, published on 8 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-208
Which versions are affected by CVE-2026-43383?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43383?
Apply the vendor's patch.
Is CVE-2026-43383 being exploited?
There is no known exploitation of CVE-2026-43383 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43383, DEBIAN-CVE-2026-43383, GHSA-m4fq-qc69-83h9, ROOT-OS-DEBIAN-11-CVE-2026-43383, ROOT-OS-UBUNTU-2204-CVE-2026-43383, ROOT-OS-UBUNTU-2404-CVE-2026-43383 and 1 more.