CVE-2026-55958CWE-393CWE-787

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

High · published June 25, 2026

CVSS v4.0
8.3
EPSS
0%
Percentile
37.2
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.3 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
EPSS
0.00443 · 37.2th percentile
Weaknesses
CWE-393 · Return of Wrong Status Code; CWE-787 · Out-of-bounds Write
Published
2026-06-25T19:35Z
EPSS history
Timeline
  • 25 JUN 19:35Z
    Renesas TSIP TLS 1.3 transcript buffer out-of-bounds write in tsip_StoreMessage
    cvelistv5