Description
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.
Published: 2026-08-20
Score: 9.3 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Thu, 20 Aug 2026 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Cesanta
Cesanta mongoose
Vendors & Products Cesanta
Cesanta mongoose

Thu, 20 Aug 2026 17:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Mongoose Built-in TLS: CA-bundle certificate chain accepted without any signature verification
Weaknesses CWE-295
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Cesanta Mongoose
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-20T17:34:50.472Z

Reserved: 2026-08-11T17:18:01.598Z

Link: CVE-2026-73251

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-20T18:16:45.743

Modified: 2026-08-20T18:16:45.743

Link: CVE-2026-73251

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-20T18:30:03Z

Weaknesses