{"id":"CVE-2026-6957","state":"PUBLISHED","title":"Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.","description":"Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659","publishedAt":"2026-05-27T14:23:50.770Z","updatedAt":"2026-05-28T03:55:34.437Z","severity":{"score":8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H","source":"Mattermost"},"assigner":"Mattermost","products":["Mattermost Mattermost"],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"1.1.5","versionType":"semver"},{"version":".0","status":"unaffected"}]}],"references":["https://mattermost.com/security-updates"],"weaknesses":["CWE-22"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/6xxx/CVE-2026-6957.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-6957","state":"PUBLISHED","datePublished":"2026-05-27T14:23:50.770Z","dateUpdated":"2026-05-28T03:55:34.437Z","assignerShortName":"Mattermost","assignerOrgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateReserved":"2026-04-24T13:23:50.185Z"},"containers":{"cna":{"title":"Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.","descriptions":[{"lang":"en","value":"Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659"}],"affected":[{"vendor":"Mattermost","product":"Mattermost","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"1.1.5","versionType":"semver"},{"version":".0","status":"unaffected"}]}],"references":[{"url":"https://mattermost.com/security-updates","name":"MMSA-2026-00659","tags":["vendor-advisory"]}],"metrics":[{"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"HIGH","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH","version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H","baseSeverity":"HIGH","baseScore":8},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-22","lang":"en","type":"CWE","description":"CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')"}]}],"providerMetadata":{"shortName":"Mattermost","orgId":"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee","dateUpdated":"2026-05-27T14:23:50.770Z"},"credits":[{"lang":"en","type":"finder","value":"Hassan Mohammed"}],"solutions":[{"value":"Update Mattermost Plugins to versions .0 or higher.","lang":"en"}],"source":{"advisory":"MMSA-2026-00659","defect":["https://mattermost.atlassian.net/browse/MM-68411"],"discovery":"{\"self\"=>\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=>\"Internal\", \"id\"=>\"10557\"}"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-27T00:00:00+00:00","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3","id":"CVE-2026-6957"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-28T03:55:34.437Z"}}]}}}