{"id":"CVE-2026-93849","state":"PUBLISHED","title":"Mattermost allows authenticated users to trigger excessive memory allocation via crafted msgpack binary WebSocket frames","description":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 Mattermost fail to apply allocation limits to the byte-string decode paths in its WebSocket msgpack decoder, which allows an authenticated remote attacker to cause excessive server memory allocation via a crafted binary WebSocket frame declaring a Bin32 payload length of up to 4,294,967,295 bytes.. Mattermost Advisory ID: MMSA-2026-00768","publishedAt":"2026-10-26T14:25:26.554Z","updatedAt":"2026-10-26T16:46:45.736Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.9.0","status":"affected","lessThanOrEqual":"11.9.1","versionType":"semver"},{"version":"11.8.0","status":"affected","lessThanOrEqual":"11.8.5","versionType":"semver"},{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.10","versionType":"semver"},{"version":"11.10.0","status":"affected","lessThanOrEqual":"11.10.1","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"},{"version":"11.7.11","status":"unaffected"},{"version":"11.10.2","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-789"],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93849.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93849","state":"PUBLISHED","datePublished":"2026-10-26T14:25:26.554Z","dateUpdated":"2026-10-26T16:46:45.736Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-09-18T18:40:09.913Z"},"containers":{"cna":{"title":"Mattermost allows authenticated users to trigger excessive memory allocation via crafted msgpack binary WebSocket frames","descriptions":[{"lang":"en","value":"Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 Mattermost fail to apply allocation limits to the byte-string decode paths in its WebSocket msgpack decoder, which allows an authenticated remote attacker to cause excessive server memory allocation via a crafted binary WebSocket frame declaring a Bin32 payload length of up to 4,294,967,295 bytes.. Mattermost Advisory ID: MMSA-2026-00768"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"11.9.0","status":"affected","lessThanOrEqual":"11.9.1","versionType":"semver"},{"version":"11.8.0","status":"affected","lessThanOrEqual":"11.8.5","versionType":"semver"},{"version":"11.7.0","status":"affected","lessThanOrEqual":"11.7.10","versionType":"semver"},{"version":"11.10.0","status":"affected","lessThanOrEqual":"11.10.1","versionType":"semver"},{"version":"11.11.0","status":"unaffected"},{"version":"11.9.2","status":"unaffected"},{"version":"11.8.6","status":"unaffected"},{"version":"11.7.11","status":"unaffected"},{"version":"11.10.2","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00768","tags":["vendor-advisory"]}],"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":[{"cweId":"CWE-789","lang":"en","type":"CWE","description":"CWE-789: Memory Allocation with Excessive Size Value"}]}],"providerMetadata":{"shortName":"Mattermost","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateUpdated":"2026-10-26T14:25:26.554Z"},"credits":[{"lang":"en","type":"finder","value":"oduoke"}],"solutions":[{"value":"Update Mattermost to versions 11.11.0, 11.9.2, 11.8.6, 11.7.11, 11.10.2 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00768","defect":["https://mattermost.atlassian.net/browse/MM-70173"],"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-93849","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-26T15:32:42.705205Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-26T16:46:45.736Z"}}]}}}