CVE-2026-33691

Summary

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 Software

VendorProductVersion RangeStatus
corerulesetcoreruleset< 3.3.9affected
corerulesetcoreruleset>= 4.0.0-rc1, < 4.25.0affected

Weaknesses

  • CWE-178: CWE-178: Improper Handling of Case Sensitivity

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References