CVE-2026-34086 AbuseFilter misuses ::userCanBitfield, exposing access-controlled information
Low 2.1
Published
Updated
Check this codebase for CVE-2026-34086 and fix it if it is affected.
What it is: CVE-2026-34086 is a low-severity vulnerability in Wikimedia Foundation AbuseFilter, published on 11 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-34086 in the wild and no public exploit code.
Affected product: Wikimedia Foundation AbuseFilter. No package-level version data is available, so check the vendor advisory linked from the reference page.
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2026-34086/ (Markdown: https://insights.sbomify.com/CVE-2026-34086/index.md)
Attackers can access restricted information due to improper use of user permission checks in the AbuseFilter extension.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-34086?
CVE-2026-34086 is a low-severity vulnerability in Wikimedia Foundation AbuseFilter, published on 11 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Vulnerability in Wikimedia Foundation AbuseFilter.
This issue affects AbuseFilter: from * before 1.43.7, 1.44.4, 1.45.2.
Weakness: CWE-20
Which versions are affected by CVE-2026-34086?
How do I fix CVE-2026-34086?
Upgrade to a fixed version.
Is CVE-2026-34086 being exploited?
There is no known exploitation of CVE-2026-34086 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-34086, GHSA-5qc5-wp75-wxgx, UBUNTU-CVE-2026-34086.