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PHP CVE-2026-33691

| EUVD-2026-18352 MEDIUM
Improper Handling of Case Sensitivity (CWE-178)
2026-04-02 GitHub_M
6.8
CVSS 3.1
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CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

4
Patch released
Apr 02, 2026 - 20:30 nvd
Patch available
EUVD ID Assigned
Apr 02, 2026 - 16:00 euvd
EUVD-2026-18352
Analysis Generated
Apr 02, 2026 - 16:00 vuln.today
CVE Published
Apr 02, 2026 - 15:03 nvd
MEDIUM 6.8

DescriptionNVD

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.

AnalysisAI

OWASP Core Rule Set (CRS) versions prior to 3.3.9 and 4.25.0 allow bypass of file upload restrictions through whitespace-padded filenames, enabling upload of dangerous executable file extensions (.php, .phar, .jsp, .jspx) that should be blocked. Remote attackers can exploit this vulnerability to upload malicious files with high confidence due to the simple nature of the bypass technique (inserting spaces before the file extension), potentially leading to remote code execution depending on web application firewall configuration and application behavior.

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Vendor StatusVendor

Ubuntu

Priority: Medium
modsecurity-crs
Release Status Version
xenial needs-triage -
bionic needs-triage -
focal needs-triage -
jammy needs-triage -
noble needs-triage -
questing needs-triage -
upstream released 3.3.9-1

Debian

modsecurity-crs
Release Status Fixed Version Urgency
bullseye vulnerable 3.3.0-1+deb11u1 -
bullseye (security) vulnerable 3.3.4-1~deb11u2 -
bookworm vulnerable 3.3.4-1 -
bookworm (security) vulnerable 3.3.4-1+deb12u1 -
trixie (security), trixie vulnerable 3.3.7-1+deb13u1 -
forky vulnerable 3.3.8-1 -
sid fixed 3.3.9-1 -
(unstable) fixed 3.3.9-1 -

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CVE-2026-33691 vulnerability details – vuln.today

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