{"id":"CVE-2026-123336","kind":"vulnerability","aliases":["CVE-2026-123336"],"related":[],"title":"JetBrains YouTrack: attachment size limit bypass via AI assistant thread conversion","description":"In JetBrains YouTrack before 2026.2.19728 the attachment size limit could be bypassed via AI assistant thread conversion","summary":"In JetBrains YouTrack before 2026.2.19728, the limit on attachment size could be bypassed when converting an AI assistant thread. The sources do not say what an attacker gains beyond exceeding the size limit.","severity":"low","cvss":3.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["jetbrains","runtime","self-hosted","youtrack"],"not_affected_if":["already-patched"],"how_to_check":"- Check the YouTrack version in the admin panel or on the server; the sources do not give a command.","fix":"- Move YouTrack to `2026.2.19728` or later.","status":"open","published_at":"2026-11-06T11:17:14+00:00","first_seen_at":"2026-11-06T11:41:28+00:00","triaged_at":"2026-11-06T11:43:52+00:00","updated_at":"2026-11-06T11:43:52+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-11-06T11:43:52Z","model":"claude-haiku-5-5","output":{"fix":"- Move YouTrack to `2026.2.19728` or later.","reach":"network","title":"JetBrains YouTrack: attachment size limit bypass via AI assistant thread conversion","impact":"low","summary":"In JetBrains YouTrack before 2026.2.19728, the limit on attachment size could be bypassed when converting an AI assistant thread. The sources do not say what an attacker gains beyond exceeding the size limit.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["youtrack","self-hosted","jetbrains"],"confidence":0.5,"fix_status":"available","needs_auth":"unknown","worst_case":"attachment size limit can be exceeded, affecting storage","analyst_note":"","how_to_check":"- Check the YouTrack version in the admin panel or on the server; the sources do not give a command.\n- unknown for other checks.","plain_action":"","needs_analyst":false,"not_affected_if":["already-patched"],"who_is_affected":"Self-hosted YouTrack instances before 2026.2.19728 that use the AI assistant feature are affected. Instances already on 2026.2.19728 or later, and JetBrains cloud-hosted YouTrack, are not covered by these sources.","user_interaction":"unknown","needs_special_setup":"yes","severity_if_unknown":"low"},"cost_usd":0.000653,"input_tokens":4177,"output_tokens":470,"severity_before":"low"},"analyst_status":null,"analyst_note":null,"search":"'-123336':14A,17A '-2026':13A,16A '2026.2.19728':28B,61C 'ai':8A,40B,70C 'assist':9A,41B,71C 'attach':3A,32B,63C 'attack':50B 'beyond':52B 'bypass':6A,36B,68C 'convers':11A,73C 'convert':38B 'could':34B,66C 'cve':12A,15A 'exceed':53B 'gain':51B 'host':22B 'jetbrain':1A,18B,25B,58C 'limit':5A,30B,56B,65C 'runtim':19B 'say':47B 'self':21B 'self-host':20B 'size':4A,33B,55B,64C 'sourc':44B 'thread':10A,42B,72C 'via':7A,69C 'youtrack':2A,23B,26B,59C","nicknames":[],"mitigations":[],"who_affected":"Self-hosted YouTrack instances before 2026.2.19728 that use the AI assistant feature are affected. Instances already on 2026.2.19728 or later, and JetBrains cloud-hosted YouTrack, are not covered by these sources.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["jetbrains","low","runtime","selfhosted","youtrack"],"campaign_type":null,"search_a":"'-123336':14A,17A '-2026':13A,16A 'ai':8A 'assist':9A 'attach':3A 'bypass':6A 'convers':11A 'cve':12A,15A 'jetbrain':1A 'limit':5A 'size':4A 'thread':10A 'via':7A 'youtrack':2A","search_b":"'2026.2.19728':28B 'ai':40B 'assist':41B 'attach':32B 'attack':50B 'beyond':52B 'bypass':36B 'convert':38B 'could':34B 'exceed':53B 'gain':51B 'host':22B 'jetbrain':18B,25B 'limit':30B,56B 'runtim':19B 'say':47B 'self':21B 'self-host':20B 'size':33B,55B 'sourc':44B 'thread':42B 'youtrack':23B,26B","search_c":"'2026.2.19728':61C 'ai':70C 'assist':71C 'attach':63C 'bypass':68C 'convers':73C 'could':66C 'jetbrain':58C 'limit':65C 'size':64C 'thread':72C 'via':69C 'youtrack':59C","first_public_at":"2026-11-06T11:17:14+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L","cvss_by":"cve@jetbrains.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123336","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123336","severity":null,"published_at":"2026-11-06T11:17:14+00:00","modified_at":"2026-11-06T11:17:14+00:00","first_seen_at":"2026-11-06T11:41:28+00:00","fetched_at":"2026-11-06T11:41:28+00:00","note":null}],"documents":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}