What is 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.
The record classifies CVE-2026-6679 under weakness classes CWE-787, CWE-190, CWE-197. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 107 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 7.5 — HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS v4.0 base score
- 8.8
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N - EPSS (FIRST)
- 0.5% probability of exploitation in the next 30 days, higher than 41.2% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 7.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-06-25, last modified 2026-06-26
Is CVE-2026-6679 being exploited?
Weaponised exploit code for CVE-2026-6679 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 27 in the Threadlinqs vulnerability feed.
- trickest/cve (trickest)
Affected products and versions
- wolfSSL: wolfSSL
How to fix CVE-2026-6679
The record marks a vendor fix as available for CVE-2026-6679. Patch reference: https://github.com/wolfSSL/wolfssl/pull/10116. Vendor advisory: https://www.wolfssl.com/docs/security-vulnerabilities/. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-6679
1 tracked threat in the Threadlinqs corpus references CVE-2026-6679, either in the campaign’s CVE list or as an indicator on the campaign record.
- Multiple WolfSSL Critical Vulnerabilities: Certificate Bypass, RCE, and Post-Quantum Weakening — CRITICAL · 2026-06-30
Sources
Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.