CVE-2026-39839Public exploitNetwork attack vector

Stored XSS via unsanitized map URL values

Published Apr 7, 2026 · Updated Apr 7, 2026

Stored XSS in Wikimedia Foundation MediaWiki Cargo before 3.8.7 allows remote authenticated users to execute script via map URLs. Cargo's map rendering fails to neutralize script-bearing HTML in stored URL values before placing those values in page output. Low-privileged content-writing access and a separate user's viewing of the affected map are required; successful exploitation runs script in that viewer's browser.

CVSS severity6.3
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in Wikimedia Foundation MediaWiki Cargo before 3.8.7 allows remote authenticated users to execute script via map URLs. Cargo's map rendering fails to neutralize script-bearing HTML in stored URL values before placing those values in page output. Low-privileged content-writing access and a separate user's viewing of the affected map are required; successful exploitation runs script in that viewer's browser.

The record

CVE
CVE-2026-39839
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Wikimedia Foundation
Product
MediaWiki Cargo
Classifications
CWE-80, CAPEC-592, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <3.8.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Wikimedia Foundation · MediaWiki Cargoversion=0 <3.8.7

Published CVSS scores

6.3Wikimedia FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
CAPEC-592Stored XSS
T1059.007JavaScript/JScript

Public exploit references

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo