Vulnerability intelligence

CVE-2026-33691

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.

CVSS Score

6.8

Medium

EPSS — Exploit Probability

3.6%

Riskier than 89% of all CVEs · checked 2026-09-08

Exploitation

Not in CISA KEV

KEV does not include every exploited vulnerability

Remediation

Patch available

Vendor fix published