CVE-2026-55958 Renesas TSIP TLS 1.3 transcript buffer out-of-bounds write in tsip_StoreMessage

What is CVE-2026-55958?

CVE-2026-55958 is a high-severity vulnerability in Wolfssl Wolfssl, published on 25 Jun 2026.

Official 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.

Weakness: CWE-787, CWE-393

Which versions are affected by CVE-2026-55958?

It affects 1 product.

Products include Wolfssl Wolfssl.

How do I fix CVE-2026-55958?

Upgrade to a fixed version.

Is CVE-2026-55958 being exploited?

There is no known exploitation of CVE-2026-55958 in the wild and no public exploit code.

Other vulnerabilities in Wolfssl Wolfssl

• CVE-2024-5991 Buffer overread in domain name matching Critical 10.0
• CVE-2021-37155 Security feature bypass in n/a Critical 9.8
• CVE-2020-36177 Memory corruption in n/a Critical 9.8
• CVE-2014-2896 Memory corruption in n/a Critical 9.8
• CVE-2014-2897 Memory corruption in n/a Critical 9.8

All Wolfssl Wolfssl vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2026-55958, GHSA-8mfx-6cpc-cr47, JLSEC-2026-734, UBUNTU-CVE-2026-55958.