CVE-2026-6679 DTLS 1.3 ACK serialization heap buffer overflow via integer truncation

What is CVE-2026-6679?

CVE-2026-6679 is a high-severity vulnerability in Wolfssl Wolfssl, published on 25 Jun 2026.

Official description

A heap buffer overflow could occur in the DTLS 1.3 ACK serialization path before the connecting peer is authenticated. The buffer overflow was due to an integer truncation when computing the length of the ACK record-number list, causing an undersized buffer to be allocated and then overrun. This affects builds using DTLS 1.3 and wolfSSL version 5.9.0 and earlier. A fix was added to the 5.9.1 release.

Weakness: CWE-787, CWE-197, CWE-190

Which versions are affected by CVE-2026-6679?

It affects 1 product.

Products include Wolfssl Wolfssl.

How do I fix CVE-2026-6679?

Upgrade to a fixed version.

Is CVE-2026-6679 being exploited?

There is no known exploitation of CVE-2026-6679 in the wild and no public exploit code.

Other vulnerabilities in Wolfssl Wolfssl

• CVE-2024-5991 Buffer overread in domain name matching Critical 10.0
• CVE-2021-37155 Security feature bypass in n/a Critical 9.8
• CVE-2020-36177 Memory corruption in n/a Critical 9.8
• CVE-2014-2896 Memory corruption in n/a Critical 9.8
• CVE-2014-2897 Memory corruption in n/a Critical 9.8

All Wolfssl Wolfssl vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-6679, GHSA-c9q2-5c67-xg9p, JLSEC-2026-753, UBUNTU-CVE-2026-6679.