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CVE-2026-73253 (GCVE-0-2026-73253)

Vulnerability from cvelistv5 – Published: 2026-08-20 17:41 – Updated: 2026-08-20 18:36
VLAI
Title
Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching
Summary
Mongoose is an embedded web server and network library. Prior to version 7.22, an on-path network attacker with a wildcard certificate for a parent domain can impersonate deeper subdomains to a client using the built-in TLS stack. The mg_tls_verify_cert_san() and mg_tls_verify_cert_cn() functions in src/tls_builtin.c call mg_match(), whose wildcard can cross DNS label boundaries, so a pattern such as *.example.com can match foo.bar.example.com. The resulting hostname verification bypass permits interception and modification of TLS traffic. This issue is fixed in version 7.22.
Severity
9.1 (Critical)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-20 18:33 UTC
CWE
  • CWE-295 - Improper Certificate Validation
Assigner
References
Impacted products
Vendor Product Version CPE status
cesanta mongoose Affected: < 7.22
guessed Create a notification for this product.
Show details on NVD website
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