CVE-2026-3471

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-3471", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-03-03T10:41:41.370Z", "datePublished": "2026-05-18T08:45:44.576Z", "dateUpdated": "2026-05-18T14:35:23.933Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "6.0.1", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.4.13", "status": "affected", "version": "0", "versionType": "semver"}, {"version": "6.2.0", "status": "unaffected"}, {"version": "6.1.1.0", "status": "unaffected"}, {"version": "5.13.5.0", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "game0v3r"}], "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": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "baseSeverity": "MEDIUM", "baseScore": 6.5}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-939: Improper Authorization in Handler for Custom URL Scheme", "cweId": "CWE-939"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00618", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost Desktop App to versions 6.2.0, 6.1.1.0, 5.13.5.0 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00618", "defect": ["https://mattermost.atlassian.net/browse/MM-67756"], "discovery": "EXTERNAL"}, "title": "Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-05-18T08:45:44.576Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-05-18T14:34:41.218853Z", "id": "CVE-2026-3471", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-18T14:35:23.933Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-3471", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-05-18T14:34:41.218853Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-18T14:34:54.906Z"}}], "cna": {"title": "Opening a window with {{javascript:alert()}} as URL causes crash in the Mattermost Desktop App", "source": {"defect": ["https://mattermost.atlassian.net/browse/MM-67756"], "advisory": "MMSA-2026-00618", "discovery": "EXTERNAL"}, "credits": [{"lang": "en", "type": "finder", "value": "game0v3r"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "6.0.1"}, {"status": "affected", "version": "0", "versionType": "semver", "lessThanOrEqual": "5.4.13"}, {"status": "unaffected", "version": "6.2.0"}, {"status": "unaffected", "version": "6.1.1.0"}, {"status": "unaffected", "version": "5.13.5.0"}], "defaultStatus": "unaffected"}], "solutions": [{"lang": "en", "value": "Update Mattermost Desktop App to versions 6.2.0, 6.1.1.0, 5.13.5.0 or higher."}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00618", "tags": ["vendor-advisory"]}], "x_generator": {"engine": "cvelib 1.8.0"}, "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"}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-939", "description": "CWE-939: Improper Authorization in Handler for Custom URL Scheme"}]}], "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-05-18T08:45:44.576Z"}}}, "cveMetadata": {"cveId": "CVE-2026-3471", "state": "PUBLISHED", "dateUpdated": "2026-05-18T14:35:23.933Z", "dateReserved": "2026-03-03T10:41:41.370Z", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "datePublished": "2026-05-18T08:45:44.576Z", "assignerShortName": "Mattermost"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "6.0.1", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.4.13", "status": "affected", "version": "0", "versionType": "semver"}, {"status": "unaffected", "version": "6.2.0"}, {"status": "unaffected", "version": "6.1.1.0"}, {"status": "unaffected", "version": "5.13.5.0"}]}], "source": "responsibledisclosure@mattermost.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*", "matchCriteriaId": "0BB3EBFF-A4E1-4545-B129-C2C7B5783B65", "versionEndIncluding": "5.4.13.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*", "matchCriteriaId": "AF47CB5E-DC44-4088-BA91-35AB01B04329", "versionEndIncluding": "6.0.1", "versionStartIncluding": "6.0.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*", "matchCriteriaId": "013D78B1-F678-48D0-8077-6380B46AD0D3", "versionEndExcluding": "6.2.0", "versionStartIncluding": "6.1.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "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"}], "id": "CVE-2026-3471", "lastModified": "2026-06-17T10:43:38.350", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-3471", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-05-18T14:34:41.218853Z", "version": "2.0.3"}}]}, "published": "2026-05-18T09:16:22.847", "references": [{"source": "responsibledisclosure@mattermost.com", "tags": ["Vendor Advisory"], "url": "https://mattermost.com/security-updates"}], "sourceIdentifier": "responsibledisclosure@mattermost.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-939"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,6.0.1]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,5.4.13]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "6.2.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "6.1.1.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "5.13.5.0"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Mattermost", "source": "cna", "vendor": "Mattermost"}, "product": "mattermost", "vendor": "mattermost"}], "created": "2026-05-18T10:30:23.070403+00:00", "updated": "2026-05-18T10:30:23.317355+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost"]}