Ad

CVE-2026-3849

MEDIUM CVSS 4.0: 6.9 EPSS 0.22%
Updated Mar 26, 2026
Wolfssl
Parameter Value
CVSS 6.9 (MEDIUM)
Affected Versions 5.6.0 — 5.9.0
Fixed In 5.9.0
Type CWE-787 (Out-of-bounds Write)
Vendor Wolfssl
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
Low
Partial disruption

CVSS Vector v4.0

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Wolfssl Wolfssl
cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
5.6.0 5.9.0