CVE-2026-5187: wolfSSL

Critical severity, CVSS 9.8. EPSS: 0.5% chance of exploitation in the next 30 days.

Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.

Affected products

• wolfSSL wolfSSL: up to and including 5.9.0

Published 2026-04-09. Last modified 2026-06-17.