Cesanta Mongoose up to 7.22 TLS Certificate Parser mg_der_to_tlv/mg_der_next out-of-bounds

Summaryinfo

A vulnerability classified as problematic has been found in Cesanta Mongoose up to 7.22. This affects the function mg_der_to_tlv/mg_der_next of the component TLS Certificate Parser. This manipulation causes out-of-bounds. This vulnerability is tracked as CVE-2026-73260. The attack is possible to be carried out remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cesanta Mongoose up to 7.22. It has been declared as problematic. Affected by this vulnerability is the function mg_der_to_tlv/mg_der_next of the component TLS Certificate Parser. The manipulation 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 availability. The summary by CVE is:

Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TLS certificate parser selected by MG_TLS_BUILTIN fails to verify that a long-form DER element length fits within the remaining certificate buffer. In mg_der_to_tlv() and mg_der_next(), a peer-controlled length can advance the parser beyond the certificate and underflow the remaining uint32_t length, causing mg_tls_parse_cert_der() to continue walking an invalid pointer. An unauthenticated malicious TLS server, or a client presenting a certificate to a server configured for client certificates, can trigger an out-of-bounds read and denial of service during the handshake. This issue is fixed in version 7.23.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-73260 since 08/11/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability 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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