What is CVE-2026-3549?

CVE-2026-3549 is a critical-severity vulnerability in Wofssl Wolfssl, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-03-19.

How severe is CVE-2026-3549?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Wofssl Wolfssl

CVE-2026-3549

Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.

Vulnerability class: Buffer Overflow

Published 2026-03-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (43.9th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 43.9% 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: 0.006 · change: +0.001

Affected products

Wofssl Wolfssl — versions 0
Wolfssl

Weakness classification (CWE)

CWE-122 — Heap-based Buffer Overflow

References

github.com/wolfSSL/wolfssl/pull/9817 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2026-3549?: CVE-2026-3549 is a critical-severity vulnerability in Wofssl Wolfssl, classified under Heap-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-03-19.
How severe is CVE-2026-3549?: Critical severity. CVSS v3 base score is 9.8 out of 10.