{"id":"CVE-2026-2456","summary":"Denial of Service via Unbounded Memory Allocation in Integration Actions","details":"Mattermost versions 11.3.x \u003c= 11.3.0, 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10 Mattermost fails to limit the size of responses from integration action endpoints, which allows an authenticated attacker to cause server memory exhaustion and denial of service via a malicious integration server that returns an arbitrarily large response when a user clicks an interactive message button.. Mattermost Advisory ID: MMSA-2026-00571","aliases":["GHSA-34g8-9fpp-46ch","GO-2026-4726"],"modified":"2026-09-18T03:46:19.951412190Z","published":"2026-03-16T11:06:44.920Z","related":["SUSE-SU-2026:1135-1","openSUSE-SU-2026:21483-1"],"database_specific":{"unresolved_ranges":[{"extracted_events":[{"introduced":"11.3.0"},{"last_affected":"11.3.0"},{"introduced":"11.2.0"},{"last_affected":"11.2.2"},{"introduced":"10.11.0"},{"last_affected":"10.11.10"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"Mattermost","cwe_ids":["CWE-789"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2456.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/2xxx/CVE-2026-2456.json"},{"type":"ADVISORY","url":"https://mattermost.com/security-updates"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-2456"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mattermost/mattermost","events":[{"introduced":"5b955468ea1ea8b56c0fb10feb258a36a767d7bb"},{"fixed":"fddd4a70bcb32eaff394a2fa5399efcd1b2ae251"},{"introduced":"25c828e8c852b62ad7bb7814cc6a69e9b4e194bb"},{"fixed":"005521aa79666e6960bc3302f6172b810f6bff3a"},{"introduced":"d27a2195068ddfa3ce17cf470f9739e4edb94b83"},{"fixed":"4082c3dcf285e4d1a386d2ef37f14f39dc5a0094"}],"database_specific":{"source":"CPE_RANGE","cpe":"cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"10.11.0"},{"fixed":"10.11.11"},{"introduced":"11.2.0"},{"fixed":"11.2.3"},{"introduced":"11.3.0"},{"fixed":"11.3.1"}]}}],"versions":["v10.11.11-rc1","v11.3.1-rc1","v10.11.10","v11.3.0-rc4","v11.3.0-rc3","v11.3.0","mattermost-redux@11.3.0","@mattermost/types@11.3.0","@mattermost/client@11.3.0","v10.11.9","v10.11.9-rc1","v10.11.8","v10.11.7","v10.11.6","v10.11.5","v10.11.4-rc3","v10.11.4","v10.11.4-rc2","v10.11.4-rc1","v10.11.3","v10.11.2-rc2","v10.11.2","v10.11.2-rc1","v10.11.1","v10.11.1-rc1","v10.11.0-rc3","v10.11.0","mattermost-redux@10.11.0","@mattermost/types@10.11.0","@mattermost/client@10.11.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-2456.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H"}]}