CVE-2026-73254

MEDIUM 5.4

Mongoose: Stored XSS via unescaped filenames in directory listing

CVSS Score

5.4

EPSS Score

0.0%

EPSS Percentile

0th

Mongoose is an embedded web server and network library. Prior to 7.22, an attacker who can create a file with an HTML payload in its name can trigger stored cross-site scripting when a user browses a directory served with MG_ENABLE_DIRLIST. The printdirentry() path called by listdir() in src/http.c URL-encodes the href but inserts the raw filesystem filename into the HTML link text. The browser executes the injected markup in the Mongoose origin, which can expose session data or permit actions as the victim. This issue is fixed in version 7.22.

CWE	CWE-79
Vendor	cesanta
Product	mongoose
Published	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-5g6j-m3pv-4f7g 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