CVE-2026-53599: Redaxo has a Mediapool isAllowedExtension bypass via multi-segment filename that leads to authenticated RCE on Apache mod_php multi-extension handlers

high Affects redaxo/source. Feed 2026.10.29.1, updated 2026-10-28; published 2026-07-31.

Redaxo has a Mediapool isAllowedExtension bypass via multi-segment filename that leads to authenticated RCE on Apache mod_php multi-extension handlers

Package: redaxo/source Composer
Affected versions: >=5.18.2 and <5.21.1
Fixed in: 5.21.1
Severity: high CVSS 7.5
Exploitation: not on CISA KEV · EPSS 1% (43.3th percentile)
Published: 2026-07-31
Source: osv.dev

References

Am I affected?

Find out in one command. phpwarden checks your composer.lock against this advisory and 20,000+ others, ranked by real-world exploitation (CISA KEV + EPSS). Free, offline, open data.

# one-time install
pip install phpwarden

# then
phpwarden deps composer.lock

Or keep it checked automatically: GitHub Action · pre-commit hook · GitLab CI · Laravel artisan command

Install docs How findings are ranked

Related advisories

CVE-2024-25298 high Code injection in REDAXO same package: redaxo/source
CVE-2025-64050 high REDAXO CMS is vulnerable to RCE attack through its template management component same package: redaxo/source
CVE-2024-46212 medium Path traversal in redaxo same package: redaxo/source
CVE-2024-50803 medium Redaxo Core CMS Cross Site Scripting (XSS) same package: redaxo/source
CVE-2026-21857 high Redaxo has Path Traversal in Backup Addon Leading to Arbitrary File Read same package: redaxo/source
CVE-2024-46209 low REDAXO CMS Cross-site Scripting vulnerability same package: redaxo/source