CVE-2026-34086

AbuseFilter misuses ::userCanBitfield, exposing access-controlled information

Published May 11, 2026 CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed
Description
Vulnerability in Wikimedia Foundation AbuseFilter.

This issue affects AbuseFilter: from * before 1.43.7, 1.44.4, 1.45.2.

Analysis

AI-generated

Technical impact

AbuseFilter exposes information that is intended to be access‑controlled, due to a misuse of the ::userCanBitfield function. The flaw allows users to obtain data about which actions or permissions are held by other users, violating confidentiality and potentially aiding adversaries in planning further attacks. The primary impact is the disclosure of privileged information, without any direct code execution or denial of service.

Affected Systems

Wikimedia Foundation AbuseFilter is affected. The vulnerability exists in versions prior to 1.43.7, 1.44.4, and 1.45.2. Any installation running these versions can potentially leak access‑controlled information.

Risk and Exploitability

The CVSS score of 2.1 indicates a low overall risk. The EPSS score is unavailable, and the vulnerability is not currently listed in the CISA KEV catalog. Attack vectors are inferred from the description to be via normal use of the AbuseFilter API, which is generally accessible to authenticated users. An attacker could request filter data and receive additional user permission details. Although exploitation is unlikely to result in further privileges, the leaked information may be valuable for reconnaissance.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade AbuseFilter to version 1.43.7 or later (including 1.44.4+ and 1.45.2+).
  • If an upgrade is not immediately possible, restrict access to AbuseFilter API endpoints to trusted administrators only.
  • Monitor API activity for anomalous requests that may indicate attempts to harvest permission data.

Generated by OpenCVE AI on May 11, 2026 at 22:46 UTC.

Tracking

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Advisories

Source ID Title
Debian DSA Debian DSA DSA-6208-1 mediawiki security update
References
History
Type Values Removed Values Added
Weaknesses CWE-200
CWE-284
Type Values Removed Values Added
Weaknesses CWE-20
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-200
CWE-284
Type Values Removed Values Added
First Time appeared Wikimedia
Wikimedia abusefilter
Vendors & Products Wikimedia
Wikimedia abusefilter
Type Values Removed Values Added
Description Vulnerability in Wikimedia Foundation AbuseFilter. This issue affects AbuseFilter: from * before 1.43.7, 1.44.4, 1.45.2.
Title AbuseFilter misuses ::userCanBitfield, exposing access-controlled information
References
Metrics cvssV4_0

{'score': 2.1, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/S:N/AU:Y'}

Weaknesses
  • CWE-20

    Improper Input Validation

Sources

Status
PUBLISHED
Assigner
wikimedia-foundation
Published
Updated
May 11, 2026, 5:33 PM
Reserved
Mar 25, 2026, 5:15 PM
Status
Awaiting Analysis
Published
May 11, 2026, 4:17 PM
Modified
Oct 26, 2026, 6:10 PM