CVE-2026-21876

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Source
https://nvd.nist.gov/vuln/detail/CVE-2026-21876
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21876.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-21876
Aliases
  • GHSA-36fv-25j3-r2c5
Downstream
Published
2026-01-08T13:55:37.102Z
Modified
2026-01-13T19:48:46.875030Z
Severity
  • 9.3 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N CVSS Calculator
Summary
OWASP CRS has multipart bypass using multiple content-type parts
Details

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.

Database specific 
{
    "cwe_ids": [
        "CWE-794"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21876.json",
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/coreruleset/coreruleset

Affected ranges

Type
GIT
Repo
https://github.com/coreruleset/coreruleset
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
83011c4512d9c91713629561c31c255da71d6bf7

Affected versions

v2.*

v2.2.5
v2.2.6
v2.2.7

v3.*

v3.0.0
v3.0.0-rc1
v3.0.0-rc2
v3.0.0-rc3
v3.0.1
v3.0.2
v3.1.0-rc1
v3.2-rc1
v3.2.0
v3.2.0-rc1
v3.2.0-rc2
v3.2.0-rc3
v3.3.0
v3.3.0-rc1
v3.3.0-rc2
v3.3.1-rc1
v3.3.2
v3.3.3
v3.3.4
v3.3.5
v3.3.6
v3.3.7

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21876.json"