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, 8:17 p.m.
Last Modified :
June 26, 2026, 6:54 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 50d2cd11-d01a-48ed-9441-5bfce9d63b27 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update the Renesas TSIP TLS implementation.
- Apply patches for the tsip_StoreMessage() function.
- Ensure strict certificate chain verification.
- Validate handshake message sizes.
Public PoC/Exploit Available at Github
CVE-2026-55958 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55958.
| URL | Resource |
|---|---|
| https://github.com/wolfSSL/wolfssl/pull/10705 | Issue Tracking Patch |
| https://www.wolfssl.com/docs/security-vulnerabilities/ | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55958 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55958
weaknesses.
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).
None
CMake C++ Shell C Makefile Batchfile Linker Script Perl FreeMarker Objective-C
The wolfSSL library is a small, fast, portable implementation of TLS/SSL for embedded devices to the cloud. wolfSSL supports up to TLS 1.3 and DTLS 1.3! Update to wolfSSL 5.9.1 for the latest CVE fixes.
ssl tls cryptography security openssl tls13 dtls https fips cryptography-api embedded-systems encryption iot trusted-execution-environment openssl-alternative c-library wolfssl cipher-suites openssl-api sniffer
C Shell Makefile Tcl Assembly C++ XS Perl C# M4
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55958 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55958 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 26, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-787 Added CPE Configuration OR *cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:* versions from (including) 5.4.0 up to (excluding) 5.9.2 Added Reference Type wolfSSL Inc.: https://github.com/wolfSSL/wolfssl/pull/10705 Types: Issue Tracking, Patch Added Reference Type wolfSSL Inc.: https://www.wolfssl.com/docs/security-vulnerabilities/ Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 26, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-55958', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-26T13:58:42.358851Z'} -
New CVE Received by [email protected]
Jun. 25, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'wolfSSL', 'product': 'wolfSSL', 'versions': [{'status': 'affected', 'version': '5.4.0', 'versionType': 'semver', 'lessThanOrEqual': '5.9.1'}], 'collectionURL': 'https://github.com/wolfSSL/wolfssl', 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-787 Added CWE CWE-393 Added Reference https://github.com/wolfSSL/wolfssl/pull/10705 Added Reference https://www.wolfssl.com/docs/security-vulnerabilities/