{"id":"CVE-2026-123839","kind":"vulnerability","aliases":["CVE-2026-123839"],"related":[],"title":"JetBrains IntelliJ IDEA: arbitrary URLs open without confirmation via port forwarding","description":"In JetBrains IntelliJ IDEA before 2026.3 opening arbitrary URLs without confirmation was possible via the Remote Development port forwarding model","summary":"In JetBrains IntelliJ IDEA before 2026.3, the Remote Development port forwarding model could open arbitrary URLs without asking the user to confirm. An attacker who can influence a forwarded port could get a victim's IDE to open a link they chose.","severity":"medium","cvss":4.7,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["intellij-idea","jetbrains","other","remote-development"],"not_affected_if":["remote-development-unused"],"how_to_check":"- Check the installed IntelliJ IDEA version under Help > About and compare it with `2026.3`.\n- Look at whether Remote Development port forwarding is in use.","fix":"- IntelliJ IDEA: move to `2026.3` or later (the sources give this as the first fixed version).","status":"open","published_at":"2026-11-06T17:17:22+00:00","first_seen_at":"2026-11-06T17:43:13+00:00","triaged_at":"2026-11-06T17:45:33+00:00","updated_at":"2026-11-06T17:45:33+00:00","category":"other","confidence":0.6,"triage":{"at":"2026-11-06T17:45:33Z","model":"claude-haiku-5-5","output":{"fix":"- IntelliJ IDEA: move to `2026.3` or later (the sources give this as the first fixed version).","reach":"network","title":"JetBrains IntelliJ IDEA: arbitrary URLs open without confirmation via port forwarding","impact":"low","summary":"In JetBrains IntelliJ IDEA before 2026.3, the Remote Development port forwarding model could open arbitrary URLs without asking the user to confirm. An attacker who can influence a forwarded port could get a victim's IDE to open a link they chose.","audience":"developers","category":"other","nicknames":[],"who_cares":["intellij-idea","jetbrains","remote-development"],"confidence":0.6,"fix_status":"available","needs_auth":"unknown","worst_case":"victim's IDE opens an attacker-chosen URL without confirmation","analyst_note":"","how_to_check":"- Check the installed IntelliJ IDEA version under Help > About and compare it with `2026.3`.\n- Look at whether Remote Development port forwarding is in use.","plain_action":"","needs_analyst":false,"not_affected_if":["remote-development-unused"],"who_is_affected":"Developers who use IntelliJ IDEA with Remote Development and port forwarding are the ones exposed. The sources do not say whether default configurations are affected, so teams not using Remote Development may be able to skip it, but this is unknown.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000678,"input_tokens":4189,"output_tokens":519,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-123839':14A,17A '-2026':13A,16A '2026.3':31B,73C 'arbitrari':4A,40B,75C 'ask':43B 'attack':49B 'chose':67B 'confirm':8A,47B,78C 'could':38B,56B 'cve':12A,15A 'develop':25B,34B,84C 'forward':11A,36B,54B,86C 'get':57B 'ide':61B 'idea':3A,20B,29B,71C 'influenc':52B 'intellij':2A,19B,28B,70C 'intellij-idea':18B 'jetbrain':1A,21B,27B,69C 'link':65B 'model':37B,87C 'open':6A,39B,63B,74C 'port':10A,35B,55B,85C 'possibl':80C 'remot':24B,33B,83C 'remote-develop':23B 'url':5A,41B,76C 'user':45B 'via':9A,81C 'victim':59B 'without':7A,42B,77C","nicknames":[],"mitigations":[],"who_affected":"Developers who use IntelliJ IDEA with Remote Development and port forwarding are the ones exposed. The sources do not say whether default configurations are affected, so teams not using Remote Development may be able to skip it, but this is unknown.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["intellijidea","jetbrains","medium","other","remotedevelopment"],"campaign_type":null,"search_a":"'-123839':14A,17A '-2026':13A,16A 'arbitrari':4A 'confirm':8A 'cve':12A,15A 'forward':11A 'idea':3A 'intellij':2A 'jetbrain':1A 'open':6A 'port':10A 'url':5A 'via':9A 'without':7A","search_b":"'2026.3':31B 'arbitrari':40B 'ask':43B 'attack':49B 'chose':67B 'confirm':47B 'could':38B,56B 'develop':25B,34B 'forward':36B,54B 'get':57B 'ide':61B 'idea':20B,29B 'influenc':52B 'intellij':19B,28B 'intellij-idea':18B 'jetbrain':21B,27B 'link':65B 'model':37B 'open':39B,63B 'port':35B,55B 'remot':24B,33B 'remote-develop':23B 'url':41B 'user':45B 'victim':59B 'without':42B","search_c":"'2026.3':73C 'arbitrari':75C 'confirm':78C 'develop':84C 'forward':86C 'idea':71C 'intellij':70C 'jetbrain':69C 'model':87C 'open':74C 'port':85C 'possibl':80C 'remot':83C 'url':76C 'via':81C 'without':77C","first_public_at":"2026-11-06T17:17:22+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N","cvss_by":"cve@jetbrains.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-123839","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123839","severity":null,"published_at":"2026-11-06T17:17:22+00:00","modified_at":"2026-11-06T17:17:22+00:00","first_seen_at":"2026-11-06T17:43:13+00:00","fetched_at":"2026-11-06T17:43:13+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"}