CVE-2026-21876

{"id": "CVE-2026-21876", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 9.3, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 4.7, "exploitabilityScore": 3.9}, {"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}]}, "published": "2026-01-08T14:15:57.087", "references": [{"url": "https://github.com/coreruleset/coreruleset/commit/80d80473abf71bd49bf6d3c1ab221e3c74e4eb83", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/coreruleset/coreruleset/commit/9917985de09a6cf38b3261faf9105e909d67a7d6", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/coreruleset/coreruleset/releases/tag/v3.3.8", "tags": ["Product", "Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/coreruleset/coreruleset/releases/tag/v4.22.0", "tags": ["Product", "Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/coreruleset/coreruleset/security/advisories/GHSA-36fv-25j3-r2c5", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/daytriftnewgen/CVE-2026-21876", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-794"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "El conjunto de reglas base de OWASP (CRS) es un conjunto de reglas gen\u00e9ricas de detecci\u00f3n de ataques para usar con firewalls de aplicaciones web compatibles. Antes de las versiones 4.22.0 y 3.3.8, la regla actual 922110 tiene un error al procesar solicitudes multipart con m\u00faltiples partes. Cuando la primera regla en una cadena itera sobre una colecci\u00f3n (como 'MULTIPART_PART_HEADERS'), las variables de captura ('TX:0', 'TX:1') se sobrescriben con cada iteraci\u00f3n. Solo el \u00faltimo valor capturado est\u00e1 disponible para la regla encadenada, lo que significa que los conjuntos de caracteres maliciosos en partes anteriores pueden pasarse por alto si una parte posterior tiene un conjunto de caracteres leg\u00edtimo. Las versiones 4.22.0 y 3.3.8 parchean el problema."}], "lastModified": "2026-04-09T16:16:26.437", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "85E31C8A-3287-4CD7-A3C8-29FB164CB229", "versionEndExcluding": "3.3.8"}, {"criteria": "cpe:2.3:a:owasp:owasp_modsecurity_core_rule_set:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "1FCBECBB-D90D-4883-81FF-F5F43C7A926C", "versionEndExcluding": "4.22.0", "versionStartIncluding": "4.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}