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CVE-2026-3549

HIGH CVSS 4.0: 8.3 EPSS 0.03%
Updated Mar 26, 2026
Heap Overflow
Parameter Value
CVSS 8.3 (HIGH)
Affected Versions before 5.9.0
Fixed In 5.9.0
Type CWE-122 (Heap-based Buffer Overflow)
Vendor Heap Overflow
Public PoC No

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.

Attack Parameters

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

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Vulnerable Products 1

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