CVE-2026-4159 wc_PKCS7_DecodeEnvelopedData 1 byte out-of-bounds read

Low 1.2 Published 19 Mar 2026 Updated 20 Mar 2026

A 1-byte out-of-bounds heap read in wolfSSL's PKCS7 decoding allows attackers to potentially disclose memory or cause crashes via crafted messages.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-4159?

CVE-2026-4159 is a low-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

1-byte OOB heap read in wc_PKCS7_DecodeEnvelopedData via zero-length encrypted content. A vulnerability existed in wolfSSL 5.8.4 and earlier, where a 1-byte out-of-bounds heap read in wc_PKCS7_DecodeEnvelopedData could be triggered by a crafted CMS EnvelopedData message with zero-length encrypted content. Note that PKCS7 support is disabled by default.

Weakness: CWE-125

Which versions are affected by CVE-2026-4159?

It affects 1 product.

Products include Wolfssl Wolfssl.

How do I fix CVE-2026-4159?

Upgrade to a fixed version.

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

Is CVE-2026-4159 being exploited?

There is no known exploitation of CVE-2026-4159 in the wild and no public exploit code.

All Wolfssl Wolfssl vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-4159, GHSA-m9r6-9wmx-24jv, JLSEC-2026-712, UBUNTU-CVE-2026-4159.