CVE-2021-30533
Google Chromium PopupBlocker Security Bypass Vulnerability
Google Chromium PopupBlocker
Insufficient policy enforcement in PopupBlocker in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass navigation restrictions via a crafted iframe.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 27 June 2022. US federal agencies were required to remediate it by 18 July 2022.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 16.7%, which is higher than 97.1% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Frequently asked questions
Is CVE-2021-30533 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2021-30533.
What does CVE-2021-30533 affect?
CVE-2021-30533 affects Google Chromium PopupBlocker. Insufficient policy enforcement in PopupBlocker in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass navigation restrictions via a crafted iframe.
How severe is CVE-2021-30533?
CVE-2021-30533 is rated MEDIUM with a CVSS base score of 6.5. EPSS puts the probability of exploitation in the next 30 days at 16.7%, higher than 97.1% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 18 July 2022.
How should organisations respond to CVE-2021-30533?
Apply the vendor patch for Google Chromium PopupBlocker as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.