CVE-2026-0669Public exploitNetwork attack vector

File disclosure via encoded path separators

Published Jan 7, 2026 · Updated Jan 7, 2026

Path traversal in Wikimedia MediaWiki Extension:CSS 1.39, 1.43, and 1.44 allows remote attackers to read resources outside its CSS path. The parser function validates stylesheet paths without first decoding encoded slash and backslash sequences, while affected web servers normalize those encodings afterward. Exploitation requires a server such as NGINX, or a suitably configured Apache server, that decodes %2F or %5C; disclosure is limited to resources the web service can return.

CVSS severity7.5
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Wikimedia MediaWiki Extension:CSS 1.39, 1.43, and 1.44 allows remote attackers to read resources outside its CSS path. The parser function validates stylesheet paths without first decoding encoded slash and backslash sequences, while affected web servers normalize those encodings afterward. Exploitation requires a server such as NGINX, or a suitably configured Apache server, that decodes %2F or %5C; disclosure is limited to resources the web service can return.

The record

CVE
CVE-2026-0669
Published
Jan 7, 2026
Updated
Jan 7, 2026
Vendor
Wikimedia Foundation
Product
MediaWiki Extension: CSS
Classifications
CWE-22, CAPEC-78, CAPEC-79, CAPEC-126, CAPEC-64, CAPEC-76, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 7, 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=1.39
  2. Affected versionversion=1.43
  3. Affected versionversion=1.44

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wikimedia Foundation · MediaWiki Extension: CSSversion=1.39; version=1.43; version=1.44

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CAPEC-78Using Escaped Slashes in Alternate Encoding
CAPEC-79Using Slashes in Alternate Encoding
CAPEC-126Path Traversal
CAPEC-64Using Slashes and URL Encoding Combined to Bypass Validation Logic
CAPEC-76Manipulating Web Input to File System Calls
T1190Exploit Public-Facing Application

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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