{"id":"CVE-2021-30533","kind":"vulnerability","aliases":["CVE-2021-30533"],"related":[],"title":"Insufficient policy enforcement in PopupBlocker in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to…","description":"Google Chromium PopupBlocker contains an insufficient policy enforcement vulnerability that allows a remote attacker to bypass navigation restrictions via a crafted iframe. This vulnerability could affect multiple web browsers that utilize Chromium, including, but not limited to, Google Chrome, Microsoft Edge, and Opera.\n\nCISA required action: Apply updates per vendor instructions.","summary":"Chromium's popup blocker has an insufficient policy enforcement flaw that lets a remote web page bypass navigation restrictions using a crafted iframe. An attacker gets a page that can navigate or open content it should be blocked from, and the flaw is listed as actively exploited.","severity":"medium","cvss":6.5,"epss":0.16742,"exploited":true,"exploited_at":"2022-06-27T00:00:00+00:00","products":[{"name":"Google Chromium PopupBlocker","fixed":[],"affected":"","ecosystem":"vendor"},{"name":"google chrome","fixed":["91.0.4472.77"],"affected":"< 91.0.4472.77","ecosystem":"vendor"},{"name":"fedoraproject fedora","fixed":[],"affected":"= 33","ecosystem":"vendor"},{"name":"fedoraproject fedora","fixed":[],"affected":"= 34","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["browser-users","chrome","chromium","edge","exploited","opera","runtime"],"not_affected_if":["fully-patched-browser"],"how_to_check":"Check the installed browser version against the vendor's patched release (sources do not give the fixed version).","fix":"Update Chrome, Edge, Opera and other Chromium-based browsers to the latest vendor release, as CISA directs.","status":"open","published_at":"2021-06-07T20:15:08+00:00","first_seen_at":"2026-10-23T19:11:52+00:00","triaged_at":"2026-10-23T21:12:30+00:00","updated_at":"2026-10-23T22:29:04+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-23T21:12:30Z","model":"claude-haiku-5-5","output":{"fix":"Update Chrome, Edge, Opera and other Chromium-based browsers to the latest vendor release, as CISA directs.\nunknown","reach":"internet","impact":"medium","summary":"Chromium's popup blocker has an insufficient policy enforcement flaw that lets a remote web page bypass navigation restrictions using a crafted iframe. An attacker gets a page that can navigate or open content it should be blocked from, and the flaw is listed as actively exploited.","category":"runtime","who_cares":["chrome","edge","opera","chromium","browser-users"],"confidence":0.6,"needs_auth":"no","worst_case":"Remote page bypasses navigation restrictions and forces unwanted navigation in the browser.","analyst_note":"Find the fixed Chrome/Chromium version and the vendor advisory for CVE-2021-30533 to fill how_to_check and fix; sources only say 'apply updates'.","how_to_check":"Check the installed browser version against the vendor's patched release (sources do not give the fixed version).\nunknown\nunknown","needs_analyst":true,"not_affected_if":["fully-patched-browser"],"user_interaction":"yes","needs_special_setup":"no","severity_if_unknown":"unknown"},"cost_usd":0.000507,"input_tokens":2905,"output_tokens":432,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':17A,20A '-30533':18A,21A '91.0.4472.77':11A 'action':132C 'activ':85B 'affect':112C 'allow':12A,97C 'appli':133C 'attack':15A,64B,100C 'block':77B 'blocker':43B 'browser':32B,115C 'browser-us':31B 'bypass':56B,102C 'chrome':8A,26A,34B,125C 'chromium':23A,35B,40B,88C,118C 'cisa':130C 'contain':90C 'content':73B 'could':111C 'craft':61B,107C 'cve':16A,19A 'edg':36B,127C 'enforc':3A,48B,94C 'exploit':37B,86B 'fedora':28A,30A 'fedoraproject':27A,29A 'flaw':49B,81B 'get':65B 'googl':7A,87C,124C 'google':22A,25A 'ifram':62B,108C 'includ':119C 'instruct':137C 'insuffici':1A,46B,92C 'let':51B 'limit':122C 'list':83B 'microsoft':126C 'multipl':113C 'navig':57B,70B,103C 'open':72B 'opera':38B,129C 'page':55B,67B 'per':135C 'polici':2A,47B,93C 'popup':42B 'popupblock':5A,89C 'popupblocker':24A 'prior':9A 'remot':14A,53B,99C 'requir':131C 'restrict':58B,104C 'runtim':39B 'updat':134C 'use':59B 'user':33B 'util':117C 'vendor':136C 'via':105C 'vulner':95C,110C 'web':54B,114C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-06-07T20:15:08+00:00","kev":{"dateAdded":"2022-06-27","dueDate":"2022-07-18","requiredAction":"Apply updates per vendor instructions.","knownRansomwareCampaignUse":"Unknown"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-30533","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-30533","severity":null,"published_at":"2022-06-27T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:52+00:00","fetched_at":"2026-10-25T12:39:23+00:00","note":null},{"source":"epss","external_id":"CVE-2021-30533","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-30533","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:45+00:00","fetched_at":"2026-10-23T19:13:45+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-30533","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-30533","severity":null,"published_at":"2021-06-07T20:15:08+00:00","modified_at":"2026-06-17T03:50:24+00:00","first_seen_at":"2026-10-23T22:29:04+00:00","fetched_at":"2026-10-23T22:29:04+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"}