Executive brief
wolfSSL is a cryptography library used to secure TLS and DTLS connections. When Raw Public Key (RPK) authentication is enabled, a malicious server can bypass client-side authentication checks by sending an unsolicited certificate type, potentially allowing an attacker to impersonate a legitimate server. This vulnerability affects TLS 1.2, TLS 1.3, and DTLS 1.2 connections.
Technical details
The vulnerability exists in wolfSSL's TLS 1.2, 1.3, and DTLS 1.2 implementations when RPK support is compiled in. The client fails to properly validate the server_cert_type negotiation, allowing a misbehaving server to inject an unsolicited RawPublicKey certificate type and bypass authentication checks. The flaw is only present in builds compiled with --enable-rpk, --enable-all, or --enable-distro flags.
Affected products
- wolfSSL wolfSSL Prior to fix in PR #11009 (merged August 2026)
Timeline
- 2026-09-27: disclosed