{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-6850", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-04-22T10:05:15.625Z", "datePublished": "2026-07-13T08:13:02.883Z", "dateUpdated": "2026-07-13T08:13:02.883Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.7.2", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.6.4", "status": "affected", "version": "11.6.0", "versionType": "semver"}, {"lessThanOrEqual": "10.11.19", "status": "affected", "version": "10.11.0", "versionType": "semver"}, {"version": "11.8.0", "status": "unaffected"}, {"version": "11.7.3", "status": "unaffected"}, {"version": "11.6.5", "status": "unaffected"}, {"version": "10.11.20", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "idr"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate the length and content of message attachment field values, which allows an authenticated attacker to cause a denial of service for all users in a channel via a post containing a specially crafted payload that triggers catastrophic backtracking in the client-side markdown parser.. Mattermost Advisory ID: MMSA-2026-00658"}], "metrics": [{"cvssV3_1": {"attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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-1333: Inefficient Regular Expression Complexity", "cweId": "CWE-1333"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00658", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00658", "defect": ["https://mattermost.atlassian.net/browse/MM-68424"], "discovery": "EXTERNAL"}, "title": "Crafted message attachment causes client-side denial of service via markdown parser regex backtracking in Mattermost", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-07-13T08:13:02.883Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.7.0,11.7.2]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.6.0,11.6.4]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[10.11.0,10.11.19]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.8.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.7.3"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.6.5"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "10.11.20"}}], "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": "2026-07-13T09:30:04.676020+00:00", "updated": "2026-07-13T09:30:04.676049+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost"]}