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.
Affected products
cesanta: mongoose
References6
- github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-… Vendor Advisory
- github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-… Vendor Advisory
- github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-… Vendor Advisory
- github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-… Vendor Advisory
- github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455… Patch
- github.com/cesanta/mongoose/releases/tag/7.23 Release Notes
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - CVSS 4.0
-
9.3
CRITICAL
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 9 · as of 10 November 2026
- CWE
- CWE-295
Could this be exploited in your environment?
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