CVE-2026-33691
MediumCVSS 6.8Exploitation Probability (EPSS)
High risk88th percentile - higher than 88% of all known CVEs
Summary
A bypass was found in OWASP Core Rule Set (CRS) before versions 3.3.9 and 4.25.0. By inserting whitespace in the filename (e.g., photo. php), files with dangerous extensions (.php, .phar, .jsp, .jspx) can be uploaded without being blocked.
Risk Assessment
An attacker can upload a malicious file to the server, potentially leading to remote code execution and compromise of the web application.
Recommendation
Update OWASP CRS to version 3.3.9 or 4.25.0, which include a fix that normalizes whitespace before checking the file extension.
Original NVD description (English source)
The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.9 and 4.25.0, a bypass was identified in OWASP CRS that allows uploading files with dangerous extensions (.php, .phar, .jsp, .jspx) by inserting whitespace padding in the filename (e.g. photo. php or shell.jsp ). The affected rules do not normalize whitespace before evaluating the file extension regex, so the dot-extension check fails to match. This issue has been patched in versions 3.3.9 and 4.25.0.