CVE-2026-3549 HIGH

CVE-2026-3549: ECH parsing heap buffer overflow

Vendor Wofssl
Product wolfSSL
Weakness CWE-122
Published March 19, 2026
Last update March 24, 2026

CVSS base score

8.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 19, 2026 CVE published
March 24, 2026 Record updated