Known exploited · Google
CVE-2021-30533: Google Chromium PopupBlocker Security Bypass Vulnerability
What it is
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.
- Vendor
- Product
- Chromium PopupBlocker
- Added to KEV
- June 27, 2022
- CISA due date
- July 18, 2022
- Ransomware use
- Unknown
- Weakness
- CWE-863: Incorrect Authorization
What CISA requires
Apply updates per vendor instructions.
Forensic triage
No
What to do now
- Find every instance of Chromium PopupBlocker you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before July 18, 2022 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
Not sure you are clear?
We check where you run it, patch or mitigate with your team, and look for signs it was already used against you.
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Train the engineers who fix it
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Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.