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CVE-2026-73253

CVE-2026-73253 · Mongoose: TLS Hostname Verification Bypass via Overly Permissive Wildcard Matching

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 9.1 · Critical · EPSS 0.3% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • mongoose

    Versions
    • < 7.22: Affected

    No fix published

  • mongoose Debian:14

    Versions
    • 7.21+ds-1
    • 7.21+ds-1~bpo13+1
    • 7.21+ds-2
    • 7.22+ds-1~bpo13+1
    Affected ranges
    • ECOSYSTEM: < 7.22+ds-1

    Update to 7.22+ds-1

  • mongoose Ubuntu:26.10

    Versions
    • 7.21+ds-1
    • 7.21+ds-2
    • 7.22+ds-1
    • 7.23+ds-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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