Cesanta Mongoose up to 7.22 TLS Stack src/tls_builtin.c mg_tls_recv_record out-of-bounds

Summaryinfo

A vulnerability categorized as critical has been discovered in Cesanta Mongoose up to 7.22. This vulnerability affects the function mg_tls_recv_record of the file src/tls_builtin.c of the component TLS Stack. Such manipulation leads to out-of-bounds. This vulnerability is uniquely identified as CVE-2026-73252. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Cesanta Mongoose up to 7.22. Affected by this issue is the function mg_tls_recv_record of the file src/tls_builtin.c of the component TLS Stack. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TLS stack selected by MG_TLS_BUILTIN in src/tls_builtin.c accepts a TLS 1.3 record whose decrypted size is exactly the 16-byte authentication tag with no plaintext or ContentType byte. In mg_tls_recv_record(), the msgsz length check permits that record and the recv_len calculation underflows to SIZE_MAX, so a later handshake step treats stale buffer contents as a trusted message with an effectively unbounded length. An unauthenticated malicious TLS peer can trigger a heap out-of-bounds read before certificate or Finished validation, causing a remote denial of service. This issue is fixed in version 7.23.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-73252 since 08/11/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 7.23 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
• 7.22

License

• open-source

Website

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

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