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.
Affected products
owasp: owasp modsecurity core rule set
References10
- github.com/coreruleset/coreruleset/security/advisories/GHSA-rw5… MitigationPatchVendor Advisory
- github.com/coreruleset/coreruleset/commit/2a8c63512811c5dd74472… Patch
- github.com/coreruleset/coreruleset/pull/4546 Issue TrackingPatch
- github.com/coreruleset/coreruleset/pull/4547 Issue TrackingPatch
- github.com/coreruleset/coreruleset/pull/4548 Patch
- github.com/coreruleset/coreruleset/releases/tag/v3.3.9 ProductRelease Notes
- github.com/coreruleset/coreruleset/releases/tag/v4.25.0 ProductRelease Notes
- seclists.org/fulldisclosure/2026/Apr/0 Mailing ListThird Party Advisory
- www.openwall.com/lists/oss-security/2026/03/29/2 Mailing ListThird Party Advisory
- www.openwall.com/lists/oss-security/2026/04/18/4
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - EPSS — exploit probability
- 4% percentile: 90 · as of 12 November 2026
- CWE
- CWE-178
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