CVE-2026-3547: wolfSSL

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Out-of-bounds read in ALPN parsing due to incomplete validation. wolfSSL 5.8.4 and earlier contained an out-of-bounds read in ALPN handling when built with ALPN enabled (HAVE_ALPN / --enable-alpn). A crafted ALPN protocol list could trigger an out-of-bounds read, leading to a potential process crash (denial of service). Note that ALPN is disabled by default, but is enabled for these 3rd party compatibility features: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic.

Affected products

• wolfSSL wolfSSL: before 5.9.0 (fixed in 5.9.0)

Published 2026-03-19. Last modified 2026-06-17.