{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-16251", "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "state": "PUBLISHED", "assignerShortName": "Mattermost", "dateReserved": "2026-07-20T07:26:18.823Z", "datePublished": "2026-10-16T07:14:59.296Z", "dateUpdated": "2026-10-16T07:14:59.296Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.10.0", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.9", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"version": "11.11.0", "status": "unaffected"}, {"version": "11.10.1", "status": "unaffected"}, {"version": "11.7.10", "status": "unaffected"}, {"version": "11.9.2", "status": "unaffected"}, {"version": "11.8.6", "status": "unaffected"}]}], "credits": [{"lang": "en", "type": "finder", "value": "alimursaliyev"}], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to limit the size of remote image responses buffered in memory during local image proxy direct fetches, which allows a remote attacker to cause memory exhaustion on the server via a crafted oversized image response.. Mattermost Advisory ID: MMSA-2026-00726"}], "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-770: Allocation of Resources Without Limits or Throttling", "cweId": "CWE-770"}]}], "references": [{"url": "https://mattermost.com/security-updates", "name": "MMSA-2026-00726", "tags": ["vendor-advisory"]}], "solutions": [{"value": "Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.", "lang": "en"}], "source": {"advisory": "MMSA-2026-00726", "defect": ["https://mattermost.atlassian.net/browse/MM-69860"], "discovery": "EXTERNAL"}, "title": "Mattermost local image proxy allows server memory exhaustion via unbounded image response buffering", "providerMetadata": {"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee", "shortName": "Mattermost", "dateUpdated": "2026-10-16T07:14:59.296Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Mattermost", "vendor": "Mattermost", "versions": [{"lessThanOrEqual": "11.10.0", "status": "affected", "version": "11.10.0", "versionType": "semver"}, {"lessThanOrEqual": "11.7.9", "status": "affected", "version": "11.7.0", "versionType": "semver"}, {"lessThanOrEqual": "11.9.1", "status": "affected", "version": "11.9.0", "versionType": "semver"}, {"lessThanOrEqual": "11.8.5", "status": "affected", "version": "11.8.0", "versionType": "semver"}, {"status": "unaffected", "version": "11.11.0"}, {"status": "unaffected", "version": "11.10.1"}, {"status": "unaffected", "version": "11.7.10"}, {"status": "unaffected", "version": "11.9.2"}, {"status": "unaffected", "version": "11.8.6"}]}], "source": "responsibledisclosure@mattermost.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to limit the size of remote image responses buffered in memory during local image proxy direct fetches, which allows a remote attacker to cause memory exhaustion on the server via a crafted oversized image response.. Mattermost Advisory ID: MMSA-2026-00726"}], "id": "CVE-2026-16251", "lastModified": "2026-10-16T08:17:12.527", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}, "published": "2026-10-16T08:17:12.527", "references": [{"source": "responsibledisclosure@mattermost.com", "url": "https://mattermost.com/security-updates"}], "sourceIdentifier": "responsibledisclosure@mattermost.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "responsibledisclosure@mattermost.com", "type": "Secondary"}]}

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