Authenticated RCE via decoded custom tag eval
Published Aug 14, 2026 · Updated Aug 14, 2026
Code injection in ImpressCMS 2.0.3 and earlier allows remote authenticated users with administrator access to execute arbitrary PHP code. The custom tag renderer decodes HTML entities with undoHtmlSpecialChars() and passes the restored PHP tag content directly to eval(), defeating HTML Purifier. Administrator access is required to store a PHP-type custom tag; the preload handler then executes the payload as the web server user on every frontend page load.
Summary
What happened
Code injection in ImpressCMS 2.0.3 and earlier allows remote authenticated users with administrator access to execute arbitrary PHP code. The custom tag renderer decodes HTML entities with undoHtmlSpecialChars() and passes the restored PHP tag content directly to eval(), defeating HTML Purifier. Administrator access is required to store a PHP-type custom tag; the preload handler then executes the payload as the web server user on every frontend page load.
The record
- CVE
- CVE-2026-73679
- Published
- Aug 14, 2026
- Updated
- Aug 14, 2026
- Vendor
- ImpressCMS
- Product
- ImpressCMS
- Classifications
- CWE-94, T1059
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Aug 14, 2026CVE publishedPublication date reported by the CVE source.
- Aug 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=2.0.3
What conditions does exploitation require?
What is affected?
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
- ImpressCMS PHP Code Injection Proof of Conceptfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo