{"id":"CVE-2026-21876","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.","aliases":["GHSA-36fv-25j3-r2c5"],"modified":"2026-08-12T03:51:37.064829259Z","published":"2026-01-08T13:55:37.102Z","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":[{"type":"WEB","url":"https://github.com/coreruleset/coreruleset/releases/tag/v3.3.8"},{"type":"WEB","url":"https://github.com/coreruleset/coreruleset/releases/tag/v4.22.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21876.json"},{"type":"ADVISORY","url":"https://github.com/coreruleset/coreruleset/security/advisories/GHSA-36fv-25j3-r2c5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21876"},{"type":"FIX","url":"https://github.com/coreruleset/coreruleset/commit/80d80473abf71bd49bf6d3c1ab221e3c74e4eb83"},{"type":"FIX","url":"https://github.com/coreruleset/coreruleset/commit/9917985de09a6cf38b3261faf9105e909d67a7d6"},{"type":"EVIDENCE","url":"https://github.com/daytriftnewgen/CVE-2026-21876"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/coreruleset/coreruleset","events":[{"introduced":"0"},{"fixed":"83011c4512d9c91713629561c31c255da71d6bf7"},{"introduced":"1d95422bb31983a5290720b7fb662ce3dd51f753"},{"fixed":"f13d4c53c449bd1055817f0f9d212eae69fdc3af"},{"fixed":"80d80473abf71bd49bf6d3c1ab221e3c74e4eb83"},{"fixed":"9917985de09a6cf38b3261faf9105e909d67a7d6"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"3.3.8"},{"introduced":"4.0.0"},{"fixed":"4.22.0"}],"source":["CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*"}}],"versions":["v3.3.7","v4.21.0","v4.20.0","v4.19.0","v4.18.0","v4.17.1","v4.17.0","v4.16.0","v4.15.0","v4.14.0","v4.13.0","v4.12.0","nightly","v4.11.0","v4.10.0","v4.9.0","v3.3.6","v4.8.0","v4.7.0","v3.3.5","v4.6.0","v4.5.0","v4.4.0","v4.3.0","v4.2.0","v4.1.0","v4.0.0","v3.3.4","v3.3.3","v3.3.2","v3.3.1-rc1","v3.3.0","v3.3.0-rc2","v3.3.0-rc1","v3.2.0-rc1","v3.2-rc1","v3.1.0-rc1","v3.0.1","v3.0.0-rc3","v3.0.0-rc2","v3.0.0-rc1","v2.2.7","v2.2.6","v2.2.5"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21876.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N"}]}