{"id":"CVE-2026-13411","kind":"vulnerability","aliases":["CVE-2026-13411"],"related":[],"title":"Mattermost Playbooks: null import condition crashes plugin for all users","description":"Mattermost versions 11.7.x <= 11.7.11 fail to validate null elements when decoding playbook import conditions which allows an authenticated attacker to crash the Playbooks plugin instance-wide via a crafted import request containing a null condition. Mattermost Advisory ID: MMSA-2026-00709","summary":"Mattermost versions 11.7.x up to 11.7.11 fail to validate null elements when decoding playbook import conditions. An authenticated user can send a crafted import request with a null condition and crash the Playbooks plugin for the whole instance.","severity":"medium","cvss":4.3,"epss":0.00321,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["mattermost","package","playbooks-plugin","self-hosted"],"not_affected_if":["auth-required","managed-hosting"],"how_to_check":"- Check the Mattermost server version with `mattermost version` or the System Console and see whether it falls in 11.7.x up to 11.7.11.\n- Confirm the Playbooks plugin is installed and enabled in the System Console under Plugin Management.","fix":"- Upgrade Mattermost to a release newer than `11.7.11` that includes the MMSA-2026-00709 fix (exact fixed version unknown from sources).\n- Until patched, restrict playbook import to trusted users.","status":"open","published_at":"2026-10-22T11:17:52+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","triaged_at":"2026-10-25T04:37:24+00:00","updated_at":"2026-10-25T04:37:24+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T04:37:24Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Mattermost to a release newer than `11.7.11` that includes the MMSA-2026-00709 fix (exact fixed version unknown from sources).\n- Until patched, restrict playbook import to trusted users.","reach":"network","title":"Mattermost Playbooks: null import condition crashes plugin for all users","impact":"low","summary":"Mattermost versions 11.7.x up to 11.7.11 fail to validate null elements when decoding playbook import conditions. An authenticated user can send a crafted import request with a null condition and crash the Playbooks plugin for the whole instance.","category":"package","nicknames":[],"who_cares":["mattermost","self-hosted","playbooks-plugin"],"confidence":0.7,"needs_auth":"yes","worst_case":"Playbooks plugin crashes for every user on the instance","analyst_note":"","how_to_check":"- Check the Mattermost server version with `mattermost version` or the System Console and see whether it falls in 11.7.x up to 11.7.11.\n- Confirm the Playbooks plugin is installed and enabled in the System Console under Plugin Management.","needs_analyst":false,"not_affected_if":["managed-hosting","auth-required"],"who_is_affected":"Self-hosted Mattermost deployments running 11.7.x up to 11.7.11 with the Playbooks plugin enabled are exposed. An attacker needs a valid account on the instance, so teams with open or public sign-up face more risk. Teams on managed hosting or without the Playbooks plugin can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000623,"input_tokens":3368,"output_tokens":573,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-00709':106C '-13411':13A,16A '-2026':12A,15A,105C '11.7':27B,66C '11.7.11':31B,68C 'advisori':102C 'allow':80C 'attack':83C 'authent':43B,82C 'condit':5A,41B,54B,78C,100C 'contain':97C 'craft':48B,94C 'crash':6A,56B,85C 'cve':11A,14A 'decod':38B,75C 'element':36B,73C 'fail':32B,69C 'host':24B 'id':103C 'import':4A,40B,49B,77C,95C 'instanc':63B,90C 'instance-wid':89C 'mattermost':1A,17B,25B,64C,101C 'mmsa':104C 'null':3A,35B,53B,72C,99C 'packag':18B 'playbook':2A,20B,39B,58B,76C,87C 'playbooks-plugin':19B 'plugin':7A,21B,59B,88C 'request':50B,96C 'self':23B 'self-host':22B 'send':46B 'user':10A,44B 'valid':34B,71C 'version':26B,65C 'via':92C 'whole':62B 'wide':91C 'x':28B,67C","nicknames":[],"mitigations":[],"who_affected":"Self-hosted Mattermost deployments running 11.7.x up to 11.7.11 with the Playbooks plugin enabled are exposed. An attacker needs a valid account on the instance, so teams with open or public sign-up face more risk. Teams on managed hosting or without the Playbooks plugin can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T11:17:52+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","cvss_by":"responsibledisclosure@mattermost.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-13411","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-13411","severity":null,"published_at":"2026-10-22T11:17:52+00:00","modified_at":"2026-10-22T17:36:46+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-13411","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-13411","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T07:15:51+00:00","fetched_at":"2026-10-24T07:15:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}