{"api_version":"1","generated_at":"2026-09-14T15:24:20+00:00","cve":"CVE-2026-86349","urls":{"html":"https://cve.report/CVE-2026-86349","api":"https://cve.report/api/cve/CVE-2026-86349.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-86349","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-86349"},"summary":{"title":"Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting","description":"Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.8, 10.11.x <= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707","state":"PUBLISHED","assigner":"Mattermost","published_at":"2026-09-14 14:17:15","updated_at":"2026-09-14 14:17:15"},"problem_types":["CWE-407","CWE-407 CWE-407: Inefficient Algorithmic Complexity"],"metrics":[{"version":"3.1","source":"responsibledisclosure@mattermost.com","type":"Secondary","score":"4.3","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","baseScore":4.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"4.3","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"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:L","version":"3.1"}}],"references":[{"url":"https://mattermost.com/security-updates","name":"https://mattermost.com/security-updates","refsource":"responsibledisclosure@mattermost.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-86349","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86349","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"affected 11.9.0 11.9.0 semver","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"affected 11.8.0 11.8.4 semver","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"affected 11.7.0 11.7.8 semver","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"affected 10.11.0 10.11.22 semver","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 11.10.0","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 11.9.1","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 11.8.5","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 11.7.9","platforms":[]},{"source":"CNA","vendor":"Mattermost","product":"Mattermost","version":"unaffected 10.11.23","platforms":[]}],"timeline":[],"solutions":[{"source":"CNA","title":"","value":"Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.9, 10.11.23 or higher.","time":"","lang":"en"}],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"tr66net","lang":"en"}],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"11.9.0","status":"affected","version":"11.9.0","versionType":"semver"},{"lessThanOrEqual":"11.8.4","status":"affected","version":"11.8.0","versionType":"semver"},{"lessThanOrEqual":"11.7.8","status":"affected","version":"11.7.0","versionType":"semver"},{"lessThanOrEqual":"10.11.22","status":"affected","version":"10.11.0","versionType":"semver"},{"status":"unaffected","version":"11.10.0"},{"status":"unaffected","version":"11.9.1"},{"status":"unaffected","version":"11.8.5"},{"status":"unaffected","version":"11.7.9"},{"status":"unaffected","version":"10.11.23"}]}],"credits":[{"lang":"en","type":"finder","value":"tr66net"}],"descriptions":[{"lang":"en","value":"Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.8, 10.11.x <= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707"}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"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:L","version":"3.1"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-407","description":"CWE-407: Inefficient Algorithmic Complexity","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-14T13:51:30.175Z","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","shortName":"Mattermost"},"references":[{"name":"MMSA-2026-00707","tags":["vendor-advisory"],"url":"https://mattermost.com/security-updates"}],"solutions":[{"lang":"en","value":"Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.9, 10.11.23 or higher."}],"source":{"advisory":"MMSA-2026-00707","defect":["https://mattermost.atlassian.net/browse/MM-69398"],"discovery":"EXTERNAL"},"title":"Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","assignerShortName":"Mattermost","cveId":"CVE-2026-86349","datePublished":"2026-09-14T13:51:30.175Z","dateReserved":"2026-09-07T09:38:22.768Z","dateUpdated":"2026-09-14T13:51:30.175Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-14 14:17:15","lastModifiedDate":"2026-09-14 14:17:15","problem_types":["CWE-407","CWE-407 CWE-407: Inefficient Algorithmic Complexity"],"metrics":{"cvssMetricV31":[{"source":"responsibledisclosure@mattermost.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","baseScore":4.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":2.8,"impactScore":1.4}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"86349","Ordinal":"1","Title":"Mattermost Server Algorithmic DoS via Unbounded Markdown Block N","CVE":"CVE-2026-86349","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"86349","Ordinal":"1","NoteData":"Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.8, 10.11.x <= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707","Type":"Description","Title":"Mattermost Server Algorithmic DoS via Unbounded Markdown Block N"}]}}}