CVE-2026-73259Public exploitNetwork attack vectorHinoki check available

Reflected XSS via unescaped decoded URI

Published Aug 20, 2026 · Updated Aug 20, 2026

Reflected cross-site scripting in Cesanta Mongoose before 7.22 allows remote attackers to execute script via a crafted directory path. The listdir() renderer reached from mg_http_serve_dir() URL-decodes the request URI and writes it into the title and h1 elements with raw formatting instead of HTML entity encoding. Exploitation requires MG_ENABLE_DIRLIST and a victim visit to an attacker-supplied link, and the injected JavaScript runs in the Mongoose origin where it can read session data or perform victim actions.

CVSS severity5.4
Medium
EPSS probability0.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Reflected cross-site scripting in Cesanta Mongoose before 7.22 allows remote attackers to execute script via a crafted directory path. The listdir() renderer reached from mg_http_serve_dir() URL-decodes the request URI and writes it into the title and h1 elements with raw formatting instead of HTML entity encoding. Exploitation requires MG_ENABLE_DIRLIST and a victim visit to an attacker-supplied link, and the injected JavaScript runs in the Mongoose origin where it can read session data or perform victim actions.

The record

CVE
CVE-2026-73259
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
Cesanta
Product
Mongoose
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 7.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cesanta · Mongooseversion=< 7.22

Published CVSS scores

5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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