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NVD Vulnerability Details :
CVE-2026-21876
Analyzed
More InfoOfficial Page
Source-security-advisories@github.com
View Known Exploited Vulnerability (KEV) details
Published At-08 Jan, 2026 | 14:15
Updated At-23 Feb, 2026 | 18:33

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.

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary3.19.3CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Primary3.15.3MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Type: Secondary
Version: 3.1
Base score: 9.3
Base severity: CRITICAL
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Type: Primary
Version: 3.1
Base score: 5.3
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CPE Matches

owasp
owasp
>>owasp_modsecurity_core_rule_set>>Versions before 3.3.8(exclusive)
cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*
owasp
owasp
>>owasp_modsecurity_core_rule_set>>Versions from 4.0.0(inclusive) to 4.22.0(exclusive)
cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*
Weaknesses
CWE IDTypeSource
CWE-794Primarysecurity-advisories@github.com
CWE ID: CWE-794
Type: Primary
Source: security-advisories@github.com
Evaluator Description

Evaluator Impact

Evaluator Solution

Vendor Statements

References
HyperlinkSourceResource
https://github.com/coreruleset/coreruleset/commit/80d80473abf71bd49bf6d3c1ab221e3c74e4eb83security-advisories@github.com
Patch
https://github.com/coreruleset/coreruleset/commit/9917985de09a6cf38b3261faf9105e909d67a7d6security-advisories@github.com
Patch
https://github.com/coreruleset/coreruleset/releases/tag/v3.3.8security-advisories@github.com
Product
Release Notes
https://github.com/coreruleset/coreruleset/releases/tag/v4.22.0security-advisories@github.com
Product
Release Notes
https://github.com/coreruleset/coreruleset/security/advisories/GHSA-36fv-25j3-r2c5security-advisories@github.com
Vendor Advisory
Exploit
Hyperlink: https://github.com/coreruleset/coreruleset/commit/80d80473abf71bd49bf6d3c1ab221e3c74e4eb83
Source: security-advisories@github.com
Resource:
Patch
Hyperlink: https://github.com/coreruleset/coreruleset/commit/9917985de09a6cf38b3261faf9105e909d67a7d6
Source: security-advisories@github.com
Resource:
Patch
Hyperlink: https://github.com/coreruleset/coreruleset/releases/tag/v3.3.8
Source: security-advisories@github.com
Resource:
Product
Release Notes
Hyperlink: https://github.com/coreruleset/coreruleset/releases/tag/v4.22.0
Source: security-advisories@github.com
Resource:
Product
Release Notes
Hyperlink: https://github.com/coreruleset/coreruleset/security/advisories/GHSA-36fv-25j3-r2c5
Source: security-advisories@github.com
Resource:
Vendor Advisory
Exploit
Change History
0Changes found

Details not found