CVE-2026-21386

{"id": "CVE-2026-21386", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-21386", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-16T18:39:00.239699Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "responsibledisclosure@mattermost.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "LOW"}, "impactScore": 1.4, "exploitabilityScore": 2.8}]}, "affected": [{"source": "responsibledisclosure@mattermost.com", "affectedData": [{"vendor": "Mattermost", "product": "Mattermost", "versions": [{"status": "affected", "version": "11.3.0", "versionType": "semver", "lessThanOrEqual": "11.3.0"}, {"status": "affected", "version": "11.2.0", "versionType": "semver", "lessThanOrEqual": "11.2.2"}, {"status": "affected", "version": "10.11.0", "versionType": "semver", "lessThanOrEqual": "10.11.10"}, {"status": "unaffected", "version": "11.4.0"}, {"status": "unaffected", "version": "11.3.1"}, {"status": "unaffected", "version": "11.2.3"}, {"status": "unaffected", "version": "10.11.11"}], "defaultStatus": "unaffected"}]}], "published": "2026-03-16T15:16:20.927", "references": [{"url": "https://mattermost.com/security-updates", "tags": ["Vendor Advisory"], "source": "responsibledisclosure@mattermost.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "responsibledisclosure@mattermost.com", "description": [{"lang": "en", "value": "CWE-203"}]}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to use consistent error responses when handling the /mute command which allows an authenticated team member to enumerate private channels they are not authorized to know about via differing error messages for nonexistent versus private channels. Mattermost Advisory ID: MMSA-2026-00588"}, {"lang": "es", "value": "Las versiones de Mattermost 11.3.x &lt;= 11.3.0, 11.2.x &lt;= 11.2.2, 10.11.x &lt;= 10.11.10 no utilizan respuestas de error consistentes al manejar el comando /mute, lo que permite a un miembro del equipo autenticado enumerar canales privados sobre los que no est\u00e1n autorizados a conocer, a trav\u00e9s de mensajes de error diferentes para canales inexistentes frente a canales privados. ID de Aviso de Mattermost: MMSA-2026-00588"}], "lastModified": "2026-06-17T10:18:36.787", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B6E5F368-358C-429B-8F04-3C8DF4A71A91", "versionEndExcluding": "10.11.11", "versionStartIncluding": "10.11.0"}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "7F64C167-943D-4F3F-9374-BCC8DECB3881", "versionEndExcluding": "11.2.3", "versionStartIncluding": "11.2.0"}, {"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "945A6E29-209F-4992-8692-BEF63DCB6B98", "versionEndExcluding": "11.3.1", "versionStartIncluding": "11.3.0"}], "operator": "OR"}]}], "sourceIdentifier": "responsibledisclosure@mattermost.com"}