{"schemaVersion":3,"id":"CVE-2026-21876","aliases":["UBUNTU-CVE-2026-21876","DEBIAN-CVE-2026-21876","DSA-6105-1"],"status":"published","duplicateOf":null,"title":null,"description":"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. 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