# CVE-2026-39933: Multiple XSS vulnerabilities in GlobalWatchlist

> Cross-site scripting vulnerabilities in the MediaWiki GlobalWatchlist extension allow attackers to inject malicious scripts, potentially compromising user sessions.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-333p-mjpr-3q3c

## What is CVE-2026-39933?

CVE-2026-39933 is a medium-severity cross-site scripting vulnerability in The Wikimedia Foundation Mediawiki - GlobalWatchlist Extension, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in The Wikimedia Foundation Mediawiki - GlobalWatchlist Extension allows Cross-Site Scripting (XSS). The issue has been remediated on the `master` branch, and in the release branches for MediaWiki versions 1.43, 1.44, and 1.45.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-39933?


## How do I fix CVE-2026-39933?

No fix has been published for CVE-2026-39933 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39933 being exploited?

There is no known exploitation of CVE-2026-39933 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39933 and fix it if it is affected.

What it is: CVE-2026-39933 is a medium-severity cross-site scripting vulnerability in The Wikimedia Foundation Mediawiki - GlobalWatchlist Extension, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-39933 in the wild and no public exploit code.

Affected product: The Wikimedia Foundation Mediawiki - GlobalWatchlist Extension. 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-2026-39933/ (Markdown: https://insights.sbomify.com/CVE-2026-39933/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39933
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39933
- OSV: https://osv.dev/vulnerability/CVE-2026-39933

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-39933/
Summaries are generated and may contain mistakes; the official description above is the record.