CVE-2026-21950

-- CVE-2026-21950 PoC - MySQL Optimizer DoS -- Author: Security Researcher -- Environment: MySQL Server 9.0.0-9.5.0 -- Note: Actual PoC requires specific query patterns targeting optimizer -- The following is a conceptual PoC structure -- Step 1: Connect to vulnerable MySQL Server mysql -u low_priv_user -p -h target_host -- Step 2: Execute crafted query targeting optimizer -- The specific query pattern exploits optimizer handling of: -- - Complex JOIN operations -- - Subqueries with specific structures -- - UNION combinations with NULL values -- Example conceptual query (actual PoC may vary): SELECT * FROM ( SELECT col1, col2 FROM table1 WHERE col1 IN ( SELECT col1 FROM table2 WHERE col2 = NULL ) ) AS subquery1 UNION SELECT NULL, NULL; -- Step 3: Observe server hang or crash -- Check MySQL error log for crash details

{"cve": {"id": "CVE-2026-21950", "sourceIdentifier": "[email protected]", "published": "2026-01-20T22:15:57.993", "lastModified": "2026-01-29T15:28:59.573", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 9.0.0-9.5.0. Easily exploitable vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.1 Base Score 6.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)."}, {"lang": "es", "value": "Vulnerabilidad en el producto MySQL Server de Oracle MySQL (componente: Server: Optimizer). Las versiones compatibles que están afectadas son 9.0.0-9.5.0. Una vulnerabilidad fácilmente explotable permite a un atacante con pocos privilegios con acceso a la red a través de múltiples protocolos comprometer MySQL Server. Los ataques exitosos de esta vulnerabilidad pueden resultar en la capacidad no autorizada de causar un cuelgue o un fallo repetible con frecuencia (DoS completo) de MySQL Server. Puntuación base CVSS 3.1 6.5 (Impactos en la disponibilidad). Vector CVSS: (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:oracle:mysql_server:*:*:*:*:*:*:*:*", "versionStartIncluding": "9.0.0", "versionEndIncluding": "9.5.0", "matchCriteriaId": "80A941A0-B16F-477B-9062-EF768F4CAAD4"}]}]}], "references": [{"url": "https://www.oracle.com/security-alerts/cpujan2026.html", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}