CVE-2026-6679
CVE-2026-6679 is a high-severity vulnerability in Wolfssl with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 7.5)
- CVSS v4: 8.8
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-39557
- Weakness: CWE-787
- Affected product: Wolfssl
- Published:
- Last modified:
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.
Frequently asked questions
- 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.
- How severe is CVE-2026-6679?
- CVE-2026-6679 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2026-6679 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-6679?
- CVE-2026-6679 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-6679?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-6679 have an EU (EUVD) identifier?
- Yes. CVE-2026-6679 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39557.
- When was CVE-2026-6679 published?
- CVE-2026-6679 was published on 2026-06-25 and last updated on 2026-06-27.
References
Affected products (1)
- cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
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