Cesanta Mongoose up to 7.21 TLS Server mg_tls_server_recv_hello session_id_len out-of-bounds

Summaryinfo

A vulnerability, which was classified as critical, was found in Cesanta Mongoose up to 7.21. The affected element is the function mg_tls_server_recv_hello of the component TLS Server. Executing a manipulation of the argument session_id_len can lead to out-of-bounds. This vulnerability appears as CVE-2026-11404. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in Cesanta Mongoose up to 7.21. This vulnerability affects the function mg_tls_server_recv_hello of the component TLS Server. The manipulation of the argument session_id_len with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Cesanta Mongoose before 7.22 contains an out-of-bounds read in the built-in TLS server function mg_tls_server_recv_hello(), which uses an attacker-controlled session_id_len byte from a TLS ClientHello as a buffer index without validating it against the length of received data. A remote, unauthenticated attacker can send a single crafted ClientHello with an oversized session id length to read past the receive buffer, crashing any HTTPS, MQTTS, or WSS service built on MG_TLS_BUILTIN.

The advisory is available at github.com. This vulnerability was named CVE-2026-11404 since 06/05/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 7.22 eliminates this vulnerability.

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Productinfo

Vendor

• Cesanta

Name

• Mongoose

Version

• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21

License

• open-source

Website

• Product: https://github.com/cesanta/mongoose/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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