Authenticated RCE via multi-extension upload validation bypass
Published Jul 31, 2026 · Updated Jul 31, 2026
Unrestricted file upload in REDAXO Core 5.18.2 through 5.21.0 allows remote authenticated users to execute PHP through a polyglot image. rex_mediapool::isAllowedExtension checks blocked extensions only at the filename end or before the final suffix, so shell.php.any.jpg passes. Exploitation requires media[upload] permission and an Apache PHP handler that treats a nonterminal .php segment as executable, yielding code execution as the web-server user.
Summary
What happened
Unrestricted file upload in REDAXO Core 5.18.2 through 5.21.0 allows remote authenticated users to execute PHP through a polyglot image. rex_mediapool::isAllowedExtension checks blocked extensions only at the filename end or before the final suffix, so shell.php.any.jpg passes. Exploitation requires media[upload] permission and an Apache PHP handler that treats a nonterminal .php segment as executable, yielding code execution as the web-server user.
The record
- CVE
- CVE-2026-53599
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- REDAXO
- Product
- REDAXO Core
- Classifications
- CWE-434, T1190, T1505.003
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 5.18.2, < 5.21.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-98pp-vccm-qm25 end-to-end proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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