CVE-2025-62665Public exploitNetwork attack vector

Stored XSS via unescaped system messages

Published Oct 18, 2025 · Updated Oct 20, 2025

Stored XSS in the Wikimedia Foundation MediaWiki BlueSky skin before 1.39 allows remote attackers to execute scripts through system messages. BlueSkyTemplate returns non-key message text unchanged, inserts it as raw HTML, and passes some sidebar labels to Linker::link without escaping. Some paths require control of a rendered system message; the login-link path instead requires the nondefault $wgUseXssLanguage setting, and injected script runs in visitors' browsers.

CVSS severity6.9
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the Wikimedia Foundation MediaWiki BlueSky skin before 1.39 allows remote attackers to execute scripts through system messages. BlueSkyTemplate returns non-key message text unchanged, inserts it as raw HTML, and passes some sidebar labels to Linker::link without escaping. Some paths require control of a rendered system message; the login-link path instead requires the nondefault $wgUseXssLanguage setting, and injected script runs in visitors' browsers.

The record

CVE
CVE-2025-62665
Published
Oct 18, 2025
Updated
Oct 20, 2025
Vendor
Wikimedia Foundation
Product
MediaWiki BlueSky skin
Classifications
CWE-79, CAPEC-592, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 20, 2025Record 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=master <1.39

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wikimedia Foundation · MediaWiki BlueSky skinversion=master <1.39

Published CVSS scores

6.9Wikimedia FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:L/SA:L

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')
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

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Your stack

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