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.
Metrics
Affected Vendors & Products
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References
History
Thu, 02 Apr 2026 15:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | OWASP CRS: Whitespace padding in filenames bypasses file upload extension checks | |
| Weaknesses | CWE-178 | |
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cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-04-02T15:25:25.719Z
Reserved: 2026-03-23T16:34:59.932Z
Link: CVE-2026-33691
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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