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{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.3.0,11.3.0]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[11.2.0,11.2.2]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[10.11.0,10.11.10]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.4.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.3.1"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "11.2.3"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "10.11.11"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Mattermost", "source": "cna", "vendor": "Mattermost"}, "product": "mattermost_server", "vendor": "mattermost"}], "analysis": {"en": {"generated_at": "2026-03-18T19:38:36.669286+00:00", "value": {"mitigation_remediation": ["Apply the official Mattermost patch to version 11.4.0, 11.3.1, 11.2.3, 10.11.11 or newer.", "After patching, verify that all Mattermost instances are running the updated version and restart services if necessary.", "If immediate patching is not viable, limit or throttle login attempts on the Mattermost servers using network or application\u2011layer controls to mitigate the impact.", "Monitor server performance and logs for unusual login traffic or memory usage spikes.", "Review the Mattermost Security Advisory MMSA-2026-00587 for additional guidance."], "summary": {"action": "Patch Now", "impact": "Denial of Service"}, "threat_synthesis": {"affected_systems": "Affected systems are Mattermost server deployments running any of the following versions: 10.11.x up to and including 10.11.10, 11.2.x up to and including 11.2.2, and 11.3.x up to and including 11.3.0. The issue is present in all Mattermost releases prior to 10.11.11, 11.2.3, and 11.3.1 respectively.", "description_and_impact": "The vulnerability arises from the Mattermost server failing to constrain excessively long passwords during authentication. Login attempts containing multi\u2011megabyte passwords consume excessive CPU cycles and memory, leading to resource exhaustion. This can result in a denial of service where legitimate users are unable to authenticate or the server becomes unresponsive. The weakness is identified as CWE\u2011770 (Resource Exhaustion).", "risk_and_exploitability": "The CVSS score for this issue is 7.5, indicating a high\u2011severity attack. EPSS indicates a low probability of exploitation (<1%). The vulnerability is not listed in the CISA KEV catalog. Exploitation requires the ability to send login requests to the server. An attacker can exploit it remotely by submitting forged authentication attempts with very large password fields, consuming server resources until the service degrades or an outage occurs."}}}}, "created": "2026-03-24T10:44:39.932970+00:00", "updated": "2026-03-30T07:02:29.536697+00:00", "vendors": ["mattermost", "mattermost$PRODUCT$mattermost_server"]}