Cesanta Mongoose up to 7.22 TLS Initialization src/tls_builtin.c mg_tls_init certificate validation

Summaryinfo

A vulnerability identified as problematic has been detected in Cesanta Mongoose up to 7.22. Affected by this issue is the function mg_tls_init of the file src/tls_builtin.c of the component TLS Initialization. Performing a manipulation results in certificate validation. This vulnerability is identified as CVE-2026-73251. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Cesanta Mongoose up to 7.22. It has been classified as problematic. This affects the function mg_tls_init of the file src/tls_builtin.c of the component TLS Initialization. The manipulation with an unknown input leads to a certificate validation vulnerability. CWE is classifying the issue as CWE-295. The product does not validate, or incorrectly validates, a certificate. This is going to have an impact on integrity. The summary by CVE is:

Mongoose is an embedded web server and network library. Prior to 7.23, a network attacker can impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. In src/tls_builtin.c, the mg_tls_init() function stores the bundle in tls->ca_bundle_der while tls->ca_der.len remains zero, and mg_tls_recv_cert() uses tls_bundle_find() to accept a Common Name match without calling mg_tls_verify_cert_signature(). A forged self-signed certificate can therefore satisfy hostname and CertificateVerify checks and enable interception, credential disclosure, traffic modification, and malicious responses. This issue is fixed in version 7.23.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-73251 since 08/11/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1587.003 for this issue.

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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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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