Buffer overflow in Wolfssl
CVE-2026-6679
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.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (40.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Wolfssl — versions 5.4.0
Weakness classification (CWE)
References
- github.com/wolfSSL/wolfssl/pull/10116 (Patch, patch, Issue Tracking)
- www.wolfssl.com/docs/security-vulnerabilities/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-6679?
- CVE-2026-6679 is a high-severity vulnerability in Wolfssl, classified under Integer Overflow or Wraparound. CVSS score: 7.5/10. Published 2026-06-25.
- How severe is CVE-2026-6679?
- High severity. CVSS v3 base score is 7.5 out of 10.