---
id: CVE-2026-73259
title: Mongoose is an embedded web server and network library
summary: >-
  Mongoose is an embedded web server and network library. Prior to 7.22, a
  remote attacker can send a crafted percent-encoded request path to a
  deployment using MG_ENABLE_DIRLIST and persuade a user to visit it. The
  mg_http_serve_dir() and…
severity: medium
cvss: 5.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N'
cwe:
  - CWE-79
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-2026-73259'
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-9cwm-487w-h25w
    label: security-advisories@github.com
  - url: >-
      https://github.com/cesanta/mongoose/security/advisories/GHSA-9cwm-487w-h25w
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00407
epssPercentile: 0.32176
ingestedAt: '2026-09-09T21:22:45.545Z'
---

## Overview

Mongoose is an embedded web server and network library. Prior to 7.22, a remote attacker can send a crafted percent-encoded request path to a deployment using MG_ENABLE_DIRLIST and persuade a user to visit it. The mg_http_serve_dir() and listdir() path in src/http.c places the decoded request URI into the title and h1 elements without HTML entity encoding. The resulting reflected cross-site scripting executes in the Mongoose origin and can expose session data or perform actions as the victim. This issue is fixed in version 7.22.

## Remediation

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