CVE-2026-21876

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Source
https://cve.org/CVERecord?id=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
DEBIAN (1)
OESA (7)
UBUNTU (1)
Published
2026-01-08T13:55:37Z
Modified
2026-10-21T02:30:34Z
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 
{
    "cna_assigner":  "GitHub_M",
    "cwe_ids":  [
        "CWE-794"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21876.json"
}
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
Introduced
1d95422bb31983a5290720b7fb662ce3dd51f753
Fixed
f13d4c53c449bd1055817f0f9d212eae69fdc3af
Fixed
80d80473abf71bd49bf6d3c1ab221e3c74e4eb83
Fixed
9917985de09a6cf38b3261faf9105e909d67a7d6
Database specific
Show details 
{
    "extracted_events":  [
        {
            "cpe":  "cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "0"
                },
                {
                    "fixed":  "3.3.8"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "cpe":  "cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*",
            "range":  [
                {
                    "introduced":  "4.0.0"
                },
                {
                    "fixed":  "4.22.0"
                }
            ],
            "source":  "CPE_RANGE"
        },
        {
            "range":  [
                {
                    "fixed":  "80d80473abf71bd49bf6d3c1ab221e3c74e4eb83"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        },
        {
            "range":  [
                {
                    "fixed":  "9917985de09a6cf38b3261faf9105e909d67a7d6"
                }
            ],
            "source":  "REFERENCES_COMMIT"
        },
        {
            "original_tag":  "v3.3.8",
            "range":  [
                {
                    "fixed":  "83011c4512d9c91713629561c31c255da71d6bf7"
                }
            ],
            "source":  "REFERENCES_TAG"
        },
        {
            "original_tag":  "v4.22.0",
            "range":  [
                {
                    "fixed":  "f13d4c53c449bd1055817f0f9d212eae69fdc3af"
                }
            ],
            "source":  "REFERENCES_TAG"
        }
    ]
}

Affected versions

Other
nightly
v2.*
v2.2.5
v2.2.6
v2.2.7
v3.*
v3.0.0-rc1
v3.0.0-rc2
v3.0.0-rc3
v3.0.1
v3.1.0-rc1
v3.2-rc1
v3.2.0-rc1
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
v4.*
v4.0.0
v4.1.0
v4.10.0
v4.11.0
v4.12.0
v4.13.0
v4.14.0
v4.15.0
v4.16.0
v4.17.0
v4.17.1
v4.18.0
v4.19.0
v4.2.0
v4.20.0
v4.21.0
v4.3.0
v4.4.0
v4.5.0
v4.6.0
v4.7.0
v4.8.0
v4.9.0

Database specific

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