CVE-2026-5772 MatchDomainName 1-Byte Stack Buffer Over-Read in Hostname Validation

Low 2.1 Published 9 Apr 2026 Updated 10 Apr 2026

A 1-byte stack buffer over-read in wolfSSL's hostname validation can cause a crash when the LEFT_MOST_WILDCARD_ONLY flag is active.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2026-5772?

CVE-2026-5772 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 9 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

A 1-byte stack buffer over-read was identified in the MatchDomainName function (src/internal.c) during wildcard hostname validation when the LEFT_MOST_WILDCARD_ONLY flag is active. If a wildcard * exhausts the entire hostname string, the function reads one byte past the buffer without a bounds check, which could cause a crash.

Weakness: CWE-126

Which versions are affected by CVE-2026-5772?

It affects 1 product.

Products include Wolfssl Wolfssl.

How do I fix CVE-2026-5772?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-5772 being exploited?

There is no known exploitation of CVE-2026-5772 in the wild and no public exploit code.

All Wolfssl Wolfssl vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-5772, GHSA-6v2v-jgg9-h79w, JLSEC-2026-740, UBUNTU-CVE-2026-5772.