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CVE PROGRAM SOURCE RECORD9.3 Critical

CVE-2026-21876

OWASP CRS has multipart bypass using multiple content-type parts

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Status
Published
Published
Updated
Assigning organization
GitHub_M

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 4.22.0 and 3.3.8, the current rule 922110 has a bug when processing multipart requests with multiple parts. When the first rule in a chain iterates over a collection (like `MULTIPART_PART_HEADERS`), the capture variables (`TX:0`, `TX:1`) get overwritten with each iteration. Only the last captured value is available to the chained rule, which means malicious charsets in earlier parts can be missed if a later part has a legitimate charset. Versions 4.22.0 and 3.3.8 patch the issue.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

coreruleset coreruleset

  • < 4.22.0affected
  • < 3.3.8affected

References