CVE-2026-5778: wolfSSL

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Integer underflow in wolfSSL packet sniffer <= 5.9.0 allows an attacker to cause a program crash in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing a large out-of-bounds read and crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.

Affected products

• wolfSSL wolfSSL: before 5.9.1 (fixed in 5.9.1)

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