#VU125939 Integer underflow in wolfSSL - CVE-2026-5188
Published: April 14, 2026
Vulnerability identifier: #VU125939
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-5188
CWE-ID: CWE-191
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
wolfSSL
wolfSSL
Software vendor:
wolfSSL
wolfSSL
Description
The vulnerability allows a remote attacker to cause incorrect handling of certificate data.
The vulnerability exists due to an integer underflow in Subject Alternative Name extension parsing when processing a malformed X.509 certificate. A remote attacker can supply a malformed certificate with an entry length larger than the enclosing sequence to cause incorrect handling of certificate data.
The issue is limited to configurations using the original ASN.1 parsing implementation, which is off by default.
Remediation
Install security update from vendor's website.