CVE-2026-73259

MEDIUM 5.4

Mongoose: Reflected XSS via decoded URI in directory listing render

CVSS Score

5.4

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-79
Vendor	cesanta
Product	mongoose
Published	Aug 20, 2026
Last Updated	Aug 20, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

cesanta / mongoose

< 7.22

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/cesanta/mongoose/security/advisories/GHSA-9cwm-487w-h25w github.com: https://github.com/cesanta/mongoose/pull/3611 github.com: https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71 github.com: https://github.com/cesanta/mongoose/releases/tag/7.22