Bug 2520650 (CVE-2026-73251)

Summary: CVE-2026-73251 mongoose: Mongoose Built-in TLS: CA-bundle certificate chain accepted without any signature verification
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: urgent    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Mongoose. When configured with a Certificate Authority (CA) bundle, the built-in Transport Layer Security (TLS) implementation matches server certificates by name without verifying their cryptographic signatures. A remote network attacker can exploit this vulnerability by presenting a forged certificate to impersonate trusted servers, allowing them to intercept encrypted communications, disclose sensitive credentials, and modify network traffic.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2543450, 2543452, 2543453, 2543456    
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Description OSIDB Bzimport 2026-08-20 17:57:07 UTC 
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.