Executive brief
wolfSSL is a security library used to provide encrypted communications for embedded devices and cloud applications. A flaw in how the library handles specific connection acknowledgement messages (DTLS 1.3) could allow an unauthenticated remote attacker to crash the service or potentially execute unauthorized code. This occurs during the initial connection phase before the identity of the connecting party is even verified.
Technical details
A heap buffer overflow exists in the DTLS 1.3 ACK serialization path of wolfSSL. The vulnerability is caused by an integer truncation error when calculating the length of the ACK record-number list. This leads to the allocation of an undersized buffer which is subsequently overrun during data serialization. The flaw is reachable by a remote, unauthenticated attacker during the handshake process. The issue affects wolfSSL versions 5.4.0 through 5.9.0 when DTLS 1.3 is enabled. A fix has been released in version 5.9.1.
Affected products
- wolfSSL wolfSSL 5.4.0 to 5.9.0
Timeline
- 2026-04-07: patched: Fix merged into master branch via PR 10116
- 2026-06-25: disclosed: CVE published to NVD