CVE-2026-3849 MEDIUM

CVE-2026-3849: Buffer Overflow in HPKE via Oversized ECH Config

Vendor Wolfssl Inc.
Product wolfSSL
Weakness CWE-787
Published March 19, 2026
Last update March 25, 2026
View on NVD All CVEs

CVSS base score

6.9/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/V:D/RE:M/U:Amber

What the vulnerability does

01Description

Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.

Key dates

02Disclosure timeline

March 19, 2026 CVE published
March 25, 2026 Record updated