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.
Published: 2026-01-08
Score: 9.3 Critical
EPSS: 3.6% Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4488-1 modsecurity-crs security update
Debian DSA Debian DSA DSA-6105-1 modsecurity-crs security update
History

Thu, 09 Apr 2026 16:15:00 +0000

Type Values Removed Values Added
References

Mon, 23 Feb 2026 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Owasp owasp Modsecurity Core Rule Set
CPEs cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*
Vendors & Products Owasp owasp Modsecurity Core Rule Set

Mon, 12 Jan 2026 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Owasp
Owasp coreruleset
Vendors & Products Owasp
Owasp coreruleset

Thu, 08 Jan 2026 18:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 08 Jan 2026 14:15:00 +0000

Type Values Removed Values Added
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.
Title OWASP CRS has multipart bypass using multiple content-type parts
Weaknesses CWE-794
References
Metrics cvssV3_1

{'score': 9.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N'}


Subscriptions

Owasp Coreruleset Owasp Modsecurity Core Rule Set
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-04-09T15:41:17.073Z

Reserved: 2026-01-05T17:24:36.927Z

Link: CVE-2026-21876

cve-icon Vulnrichment

Updated: 2026-01-08T14:52:52.629Z

cve-icon NVD

Status : Modified

Published: 2026-01-08T14:15:57.087

Modified: 2026-04-09T16:16:26.437

Link: CVE-2026-21876

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-14T15:00:12Z

Weaknesses