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CVE-2026-33691

MEDIUM

6.8

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.

CVE Details

CVSS v3.1 Score6.8

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

Attack VectorNETWORK

ComplexityHIGH

Privileges RequiredNONE

User InteractionNONE

Published4/2/2026

Last Modified4/3/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-178

References

https://github.com/coreruleset/coreruleset/commit/2a8c63512811c5dd74472becebb79a783e68ff02(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/pull/4546(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/pull/4547(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/pull/4548(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/releases/tag/v3.3.9(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/releases/tag/v4.25.0(security-advisories@github.com)

https://github.com/coreruleset/coreruleset/security/advisories/GHSA-rw5f-9w43-gv2w(security-advisories@github.com)

http://seclists.org/fulldisclosure/2026/Apr/0(af854a3a-2127-422b-91ae-364da2661108)

http://www.openwall.com/lists/oss-security/2026/03/29/2(af854a3a-2127-422b-91ae-364da2661108)

IOC Correlations

No correlations recorded

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