{"id":"CVE-2026-86044","kind":"vulnerability","aliases":["CVE-2026-86044"],"related":[],"title":"JupyterLab Desktop: crafted notebook link leaks token, enables code execution","description":"JupyterLab Desktop is the cross-platform desktop application for JupyterLab. Prior to 4.6.2-1, JupyterLab Desktop exposed getServerInfo to the renderer without confirming that the current page still had the local Jupyter server origin. In a local managed session using JupyterLab before 4.4.8, an attacker can place a crafted MathJax link in an untrusted notebook. If a victim opens the notebook and clicks the link, the existing renderer navigates to an attacker-controlled site while retaining access to the preload bridge. The site can call getServerInfo to obtain the local server URL and authentication token, then use the Jupyter REST API to create and trust a notebook that executes arbitrary code as the victim. Users whose environment already uses JupyterLab 4.4.8 or later are unaffected because the corrected link handling breaks the first step of the chain. This vulnerability is fixed in 4.6.2-1.","summary":"JupyterLab Desktop exposes a bridge that returns the local Jupyter server URL and auth token to any page the window navigates to. A crafted MathJax link in an untrusted notebook, once clicked, lets an attacker's site read that token and run arbitrary code as the user.","severity":"critical","cvss":9.6,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["data-science","jupyterlab","jupyterlab-desktop","package","python"],"not_affected_if":["jupyterlab-4.4.8-or-later","no-desktop-app","untrusted-notebooks-never-opened"],"how_to_check":"- Check the installed JupyterLab Desktop version against `4.6.2-1`.\n- Check the JupyterLab version used in local managed sessions against `4.4.8`.","fix":"- JupyterLab Desktop: `4.6.2-1`\n- JupyterLab: `4.4.8` or later (per the description)","status":"open","published_at":"2026-11-06T21:17:12+00:00","first_seen_at":"2026-11-06T21:45:08+00:00","triaged_at":"2026-11-06T21:46:30+00:00","updated_at":"2026-11-06T21:46:30+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-11-06T21:46:30Z","model":"claude-haiku-5-5","output":{"fix":"- JupyterLab Desktop: `4.6.2-1`\n- JupyterLab: `4.4.8` or later (per the description)","reach":"local","title":"JupyterLab Desktop: crafted notebook link leaks token, enables code execution","impact":"high","summary":"JupyterLab Desktop exposes a bridge that returns the local Jupyter server URL and auth token to any page the window navigates to. A crafted MathJax link in an untrusted notebook, once clicked, lets an attacker's site read that token and run arbitrary code as the user.","audience":"businesses","category":"package","nicknames":[],"who_cares":["jupyterlab","jupyterlab-desktop","python","data-science"],"confidence":0.7,"fix_status":"available","needs_auth":"no","worst_case":"attacker runs arbitrary code as the logged-in user","analyst_note":"","how_to_check":"- Check the installed JupyterLab Desktop version against `4.6.2-1`.\n- Check the JupyterLab version used in local managed sessions against `4.4.8`.","plain_action":"","needs_analyst":false,"not_affected_if":["jupyterlab-4.4.8-or-later","no-desktop-app","untrusted-notebooks-never-opened"],"who_is_affected":"Teams running JupyterLab Desktop or a local managed JupyterLab session on a workstation with JupyterLab before 4.4.8 are exposed. A victim must open an untrusted notebook and click a crafted link. Users already on JupyterLab 4.4.8 or later are unaffected per the description.","user_interaction":"yes","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000738,"input_tokens":4467,"output_tokens":583,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-1':87C,218C '-2026':12A,15A '-86044':13A,16A '4.4.8':116C,195C '4.6.2':86C,217C 'access':151C 'alreadi':192C 'api':175C 'applic':81C 'arbitrari':68B,184C 'attack':60B,118C,146C 'attacker-control':145C 'auth':39B 'authent':168C 'break':205C 'bridg':30B,155C 'call':159C 'chain':211C 'click':57B,136C 'code':9A,69B,185C 'confirm':96C 'control':147C 'correct':202C 'craft':3A,49B,122C 'creat':177C 'cross':78C 'cross-platform':77C 'current':99C 'cve':11A,14A 'data':18B 'data-sci':17B 'desktop':2A,23B,27B,74C,80C,89C 'enabl':8A 'environ':191C 'execut':10A,183C 'exist':140C 'expos':28B,90C 'first':207C 'fix':215C 'getserverinfo':91C,160C 'handl':204C 'jupyt':35B,105C,173C 'jupyterlab':1A,20B,22B,26B,73C,83C,88C,114C,194C 'jupyterlab-desktop':21B 'later':197C 'leak':6A 'let':58B 'link':5A,51B,124C,138C,203C 'local':34B,104C,110C,164C 'manag':111C 'mathjax':50B,123C 'navig':46B,142C 'notebook':4A,55B,128C,134C,181C 'obtain':162C 'open':132C 'origin':107C 'packag':24B 'page':43B,100C 'place':120C 'platform':79C 'preload':154C 'prior':84C 'python':25B 'read':63B 'render':94C,141C 'rest':174C 'retain':150C 'return':32B 'run':67B 'scienc':19B 'server':36B,106C,165C 'session':112C 'site':62B,148C,157C 'step':208C 'still':101C 'token':7A,40B,65B,169C 'trust':179C 'unaffect':199C 'untrust':54B,127C 'url':37B,166C 'use':113C,171C,193C 'user':72B,189C 'victim':131C,188C 'vulner':213C 'whose':190C 'window':45B 'without':95C","nicknames":[],"mitigations":[],"who_affected":"Teams running JupyterLab Desktop or a local managed JupyterLab session on a workstation with JupyterLab before 4.4.8 are exposed. A victim must open an untrusted notebook and click a crafted link. Users already on JupyterLab 4.4.8 or later are unaffected per the description.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["critical","datascience","jupyterlab","jupyterlabdesktop","package","python"],"campaign_type":null,"search_a":"'-2026':12A,15A '-86044':13A,16A 'code':9A 'craft':3A 'cve':11A,14A 'desktop':2A 'enabl':8A 'execut':10A 'jupyterlab':1A 'leak':6A 'link':5A 'notebook':4A 'token':7A","search_b":"'arbitrari':68B 'attack':60B 'auth':39B 'bridg':30B 'click':57B 'code':69B 'craft':49B 'data':18B 'data-sci':17B 'desktop':23B,27B 'expos':28B 'jupyt':35B 'jupyterlab':20B,22B,26B 'jupyterlab-desktop':21B 'let':58B 'link':51B 'local':34B 'mathjax':50B 'navig':46B 'notebook':55B 'packag':24B 'page':43B 'python':25B 'read':63B 'return':32B 'run':67B 'scienc':19B 'server':36B 'site':62B 'token':40B,65B 'untrust':54B 'url':37B 'user':72B 'window':45B","search_c":"'-1':87C,218C '4.4.8':116C,195C '4.6.2':86C,217C 'access':151C 'alreadi':192C 'api':175C 'applic':81C 'arbitrari':184C 'attack':118C,146C 'attacker-control':145C 'authent':168C 'break':205C 'bridg':155C 'call':159C 'chain':211C 'click':136C 'code':185C 'confirm':96C 'control':147C 'correct':202C 'craft':122C 'creat':177C 'cross':78C 'cross-platform':77C 'current':99C 'desktop':74C,80C,89C 'environ':191C 'execut':183C 'exist':140C 'expos':90C 'first':207C 'fix':215C 'getserverinfo':91C,160C 'handl':204C 'jupyt':105C,173C 'jupyterlab':73C,83C,88C,114C,194C 'later':197C 'link':124C,138C,203C 'local':104C,110C,164C 'manag':111C 'mathjax':123C 'navig':142C 'notebook':128C,134C,181C 'obtain':162C 'open':132C 'origin':107C 'page':100C 'place':120C 'platform':79C 'preload':154C 'prior':84C 'render':94C,141C 'rest':174C 'retain':150C 'server':106C,165C 'session':112C 'site':148C,157C 'step':208C 'still':101C 'token':169C 'trust':179C 'unaffect':199C 'untrust':127C 'url':166C 'use':113C,171C,193C 'user':189C 'victim':131C,188C 'vulner':213C 'whose':190C 'without':95C","first_public_at":"2026-07-24T09:50:23+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-86044","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-86044","severity":null,"published_at":"2026-11-06T21:17:12+00:00","modified_at":"2026-11-06T21:17:12+00:00","first_seen_at":"2026-11-06T21:45:08+00:00","fetched_at":"2026-11-06T21:45:08+00:00","note":null}],"documents":[{"id":90365,"url":"https://github.com/jupyterlab/jupyterlab-desktop/commit/7f8f64ae796efae77d106612c95f0edd6c5dc273","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":90286,"url":"https://github.com/jupyterlab/jupyterlab-desktop/releases/tag/v4.6.2-1","title":"Release notes: github.com","kind":"release","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Release notes: github.com"},{"id":90367,"url":"https://github.com/jupyterlab/jupyterlab-desktop/security/advisories/GHSA-2mr8-962v-wc67","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-07-24T09:50:23+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}