CVE-2026-12985

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-12985", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-06-23T11:43:37.353Z", "datePublished": "2026-09-14T14:09:53.799Z", "dateUpdated": "2026-09-15T03:56:02.615Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.9.0", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.4", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.7", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"version": "11.10.0", "status": "unaffected"}, {"version": "11.9.1", "status": "unaffected"}, {"version": "11.8.5", "status": "unaffected"}, {"version": "11.7.8", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "aryangurjarf401a3"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N", "baseSeverity": "MEDIUM", "baseScore": 6.8}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "description": "CWE-601: URL Redirection to Untrusted Site (\u201cOpen Redirect\u201d)", "cweId": "CWE-601"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00700", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00700", "defect": ["https://mattermost.atlassian.net/browse/MM-69360"], "discovery": "EXTERNAL"}, "title": "Mattermost DCR redirect URI allowlist bypass via improper URL component validation", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-09-14T14:09:53.799Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-09-14T00:00:00+00:00", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3", "id": "CVE-2026-12985"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-15T03:56:02.615Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-12985", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-09-14T19:12:54.322562Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-14T19:15:18.803Z"}}], "cna": {"title": "Mattermost DCR redirect URI allowlist bypass via improper URL component validation", "source": {"defect": ["https://mattermost.atlassian.net/browse/MM-69360"], "advisory": "MMSA-2026-00700", "discovery": "EXTERNAL"}, "credits": [{"lang": "en", "type": "finder", "value": "aryangurjarf401a3"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.8, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "11.9.0", "versionType": "semver", "lessThanOrEqual": "11.9.0"}, {"status": "affected", "version": "11.8.0", "versionType": "semver", "lessThanOrEqual": "11.8.4"}, {"status": "affected", "version": "11.7.0", "versionType": "semver", "lessThanOrEqual": "11.7.7"}, {"status": "unaffected", "version": "11.10.0"}, {"status": "unaffected", "version": "11.9.1"}, {"status": "unaffected", "version": "11.8.5"}, {"status": "unaffected", "version": "11.7.8"}], "defaultStatus": "unaffected"}], "solutions": [{"lang": "en", "value": "Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.8 or higher."}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00700", "tags": ["vendor-advisory"]}], "x_generator": {"engine": "cvelib 1.8.0"}, "descriptions": [{"lang": "en", "value": "Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700"}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-601", "description": "CWE-601: URL Redirection to Untrusted Site (\u201cOpen Redirect\u201d)"}]}], "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-09-14T14:09:53.799Z"}}}, "cveMetadata": {"cveId": "CVE-2026-12985", "state": "PUBLISHED", "dateUpdated": "2026-09-15T03:56:02.615Z", "dateReserved": "2026-06-23T11:43:37.353Z", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "datePublished": "2026-09-14T14:09:53.799Z", "assignerShortName": "Mattermost"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.9.0", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.4", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.7", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"status": "unaffected", "version": "11.10.0"}, {"status": "unaffected", "version": "11.9.1"}, {"status": "unaffected", "version": "11.8.5"}, {"status": "unaffected", "version": "11.7.8"}]}], "source": "responsibledisclosure@mattermost.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "D2DA84D0-1DE9-4846-88A0-377A6AE7FF7F", "versionEndExcluding": "11.7.8", "versionStartIncluding": "11.7.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "28B7B007-C6AE-43A8-8E34-67A52789DC27", "versionEndExcluding": "11.8.5", "versionStartIncluding": "11.8.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "matchCriteriaId": "AAA4200F-4BD8-4E69-A405-81E98F6208D5", "versionEndExcluding": "11.9.1", "versionStartIncluding": "11.9.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 Mattermost failed to validate Dynamic Client Registration redirect URIs by URL component (matching glob patterns against the raw URI string instead) which allows a remote unauthenticated attacker to register an OAuth client with an attacker-controlled callback host that bypasses the configured redirect URI allowlist via a crafted redirect URI that places an allowlisted host/path suffix inside the query string.. Mattermost Advisory ID: MMSA-2026-00700"}], "id": "CVE-2026-12985", "lastModified": "2026-10-07T17:58:56.437", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.2, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 9.3, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.8, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-12985", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-09-14T00:00:00+00:00", "version": "2.0.3"}}]}, "published": "2026-09-14T15:17:04.270", "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-601"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.9.0,11.9.0]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.8.0,11.8.4]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.7.0,11.7.7]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.10.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.9.1"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.8.5"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.7.8"}}], "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": "2026-09-15T05:00:14.028717+00:00", "updated": "2026-09-15T07:15:17.450320+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost"]}