{"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":"2026-04-10T05:39:13.593021Z","published":"2026-01-08T13:55:37.102Z","database_specific":{"cwe_ids":["CWE-794"],"cna_assigner":"GitHub_M","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21876.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/coreruleset/coreruleset","events":[{"introduced":"1d95422bb31983a5290720b7fb662ce3dd51f753"},{"fixed":"83011c4512d9c91713629561c31c255da71d6bf7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21876.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N"}]}