Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-73259

CVE-2026-73259MEDIUM

cesanta mongoose — Mongoose: Reflected XSS via decoded URI in directory listing render

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   R  U  L  L  N    5.4   .0041   32.7     —

AFFECTED
  Product   Versions  Fixed
  mongoose  < 7.22 –  —

TIMELINE
  Aug 11  Reserved by GitHub_M
  Aug 20  Published (CNA: GitHub_M)
  Sep 29  EXPLOIT PUBLISHED — CVE-2026-73259 (cesanta mongoose). Public exploit reference added.

CWE-79 · CNA: GitHub_M · CVSS v3.1 · 4 references · NVD status: Analyzed

Description

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
August 11, 2026	Reserved	Reserved by GitHub_M
August 20, 2026	Published	Published (CNA: GitHub_M)
September 29, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73259 (cesanta mongoose). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
cesanta	mongoose	—	< 7.22	—

Weaknesses

CWE-79

References (4)

https://github.com/cesanta/mongoose/commit/a9df523f76f43a38bd53b4232b9cfd4c16869e71 [Patch]
https://github.com/cesanta/mongoose/pull/3611 [Issue Tracking, Patch]
https://github.com/cesanta/mongoose/releases/tag/7.22 [Release Notes]
https://github.com/cesanta/mongoose/security/advisories/GHSA-9cwm-487w-h25w [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-73259 at cve.org

Vendors: cesanta

Weaknesses: CWE-79

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-73259 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.