CVE-2026-73251

Aliases:DEBIAN-CVE-2026-73251
Received
Published: 20 Aug 2026, 17:34
Last modified:20 Aug 2026, 17:34

Vulnerability Summary

Overall Risk (default)
high
70/100
CVSS Score
9.3 CRITICAL
v4.0 (cve.org)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

20 Aug 2026, 17:34
Published
Vulnerability first disclosed

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.

CVSS Metrics

  • v4.0•CRITICAL•Score: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
  • v4.0•CRITICAL•Score: 9.3CVSS: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

Techniques & Countermeasures

  • CWE-295•Improper Certificate Validation

    The product does not validate, or incorrectly validates, a certificate.

Affected Systems

  • cesanta•mongoose

    < 7.23

  • debian•mongoose

    all | < 7.23+ds-1

References (4)