Executive brief
A memory corruption vulnerability exists in wolfSSL when used with Renesas TSIP hardware for TLS 1.3 connections. This component is responsible for secure communications on embedded devices. A malicious server or a man-in-the-middle could send an oversized security certificate or handshake message to crash the device, potentially leading to a denial of service.
Technical details
An out-of-bounds write exists in the Renesas TSIP TLS 1.3 transcript buffer within the `tsip_StoreMessage()` function. The root cause is a logic error where a capacity check against `MSGBAG_SIZE` (8 KB) correctly identifies an overflow and sets an error code (`MEMORY_E`), but fails to return from the function. Consequently, execution proceeds to an `XMEMCPY` call that writes data past the end of the fixed-size buffer, corrupting adjacent heap memory. This vulnerability is reachable by a remote attacker (malicious server) sending an unusually large certificate chain or handshake message. It specifically affects wolfSSL builds using the Renesas TSIP TLS port (`WOLFSSL_RENESAS_TSIP_TLS`) on Renesas MCUs with TSIP hardware enabled. The issue is fixed in wolfSSL version 5.9.1.
Affected products
- wolfSSL wolfSSL 5.4.0 to 5.9.1
Timeline
- 2026-06-16: patched: Pull request 10705 merged to fix the issue.
- 2026-06-25: advisory: NVD and wolfSSL security advisory published.