Executive brief
wolfSSL is a security library used to provide encrypted communications for applications and embedded devices. A flaw in how the library handles certain advanced encryption handshakes (Post-Quantum Cryptography) could allow a malicious server to crash a client application. This occurs when the server sends a specially malformed security key, causing the library to improperly handle memory and potentially lead to a service disruption.
Technical details
A use-after-free (UAF) and double-free vulnerability exists in wolfSSL's TLS 1.3 client-side processing of PQC hybrid KeyShares. This is an incomplete fix for a previous issue (CVE-2026-5460). The root cause is located in `TLSX_KeyShare_ProcessPqcHybridClient`, where the error cleanup path may operate on or free a pointer that has already been released if the ECDH portion of a hybrid key share is malformed or truncated. An attacker acting as a malicious TLS 1.3 server can trigger this by sending a crafted ServerHello. The vulnerability is addressed by ensuring the key pointer is set to NULL after processing to prevent double-freeing during cleanup. A fix is available in the wolfSSL master branch via pull request #10327.
Affected products
- wolfSSL wolfSSL 5.8.0 to 5.9.1
Timeline
- 2026-04-27: other: Fix submitted via GitHub pull request #10327
- 2026-05-05: patched: Fix merged into master branch
- 2026-06-25: advisory: NVD publication date