8.3
HIGH CVSS 4.0
CVE-2026-55958
Renesas TSIP TLS 1.3 transcript buffer out-of-bounds write in tsip_StoreMessage
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.

INFO

Published Date :

June 25, 2026, 7:35 p.m.

Last Modified :

June 25, 2026, 7:35 p.m.

Remotely Exploit :

Yes !

Source :

wolfSSL
Affected Products

The following products are affected by CVE-2026-55958 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

No affected product recoded yet

CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 4.0 HIGH 50d2cd11-d01a-48ed-9441-5bfce9d63b27
Solution
Update TSIP TLS to fix out-of-bounds write in transcript buffer handling.
  • Update the Renesas TSIP TLS implementation.
  • Apply patches for the tsip_StoreMessage() function.
  • Ensure strict certificate chain verification.
  • Validate handshake message sizes.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

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EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.