Vulnerability Description
Out-of-bounds write in the Renesas TSIP TLS 1.3 transcript buffer. In tsip_StoreMessage() the capacity check guarding the fixed message bag (MSGBAG_SIZE) sets an error code but fails to return, so execution falls through to an XMEMCPY that writes past the end of the buffer once the accumulated TLS 1.3 handshake transcript exceeds MSGBAG_SIZE (8 KB), corrupting adjacent heap state and potentially causing a remote denial of service crash. The bag is sized to hold a normal handshake, so this is reached only by an unusually large but valid certificate chain, or by a malicious or man-in-the-middle server sending an oversized handshake message to a client that does not strictly verify the chain. This only affects builds using the Renesas TSIP TLS port (WOLFSSL_RENESAS_TSIP_TLS) as a TLS 1.3 client on Renesas MCUs with TSIP hardware enabled, and is rated High within those builds. All other configurations are unaffected.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Wolfssl | Wolfssl | >= 5.4.0, < 5.9.2 |
Related Weaknesses (CWE)
References
- https://github.com/wolfSSL/wolfssl/pull/10705Issue TrackingPatch
- https://www.wolfssl.com/docs/security-vulnerabilities/Vendor Advisory
FAQ
What is CVE-2026-55958?
CVE-2026-55958 is a vulnerability with a CVSS score of 7.5 (HIGH). Out-of-bounds write in the Renesas TSIP TLS 1.3 transcript buffer. In tsip_StoreMessage() the capacity check guarding the fixed message bag (MSGBAG_SIZE) sets an error code but fails to return, so exe...
How severe is CVE-2026-55958?
CVE-2026-55958 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-55958?
Check the references section above for vendor advisories and patch information. Affected products include: Wolfssl Wolfssl.