---
id: CVE-2026-73253
title: Mongoose is an embedded web server and network library
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…
severity: none
cwe:
  - CWE-295
published: '2026-08-20'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:19:49.197'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-73253'
references:
  - url: >-
      https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71
    label: security-advisories@github.com
  - url: 'https://github.com/cesanta/mongoose/pull/3611'
    label: security-advisories@github.com
  - url: 'https://github.com/cesanta/mongoose/releases/tag/7.22'
    label: security-advisories@github.com
  - url: >-
      https://github.com/cesanta/mongoose/security/advisories/GHSA-jp6g-796f-39vp
    label: security-advisories@github.com
  - url: >-
      https://github.com/cesanta/mongoose/security/advisories/GHSA-jp6g-796f-39vp
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00212
epssPercentile: 0.11812
ingestedAt: '2026-09-09T21:22:45.545Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.