CVE-2021-30533: Google Chromium PopupBlocker Security Bypass Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 27 Jun 2022, 385 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 16.7%
EPSS score, percentile 97 of all scored records
- How severe?
- 6.5 Medium
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA deadline 18 Jul 2022. Apply updates per vendor instructions.
- Which versions are affected?
Affected
- before 91.0.4472.77
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 18 July 2022.
Advisories and patches
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | before 91.0.4472.77 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2021-30533 to its Known Exploited Vulnerabilities (KEV) catalog on 27 Jun 2022.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 18 Jul 2022.
- The CVE record was published on 7 Jun 2021, 385 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 6.5 (Medium), taken from CISA's enrichment of the record.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 16.7% (percentile 97), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-863: Incorrect Authorization
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 7 Jun 2021 | CVE record published |
| 27 Jun 2022 | Added to CISA KEV |
| 18 Jul 2022 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
References
More exploited Google vulnerabilities
- CVE-2026-111497: Google Brotli Unchecked Return Value Vulnerability
- CVE-2026-58704: Google Pixel Improper Authorization Vulnerability
- CVE-2026-87491: Google Chromium V8 Out of Bounds Write Vulnerability
- CVE-2026-85046: Google Chromium V8 Type Confusion Vulnerability
- CVE-2026-11645: Google Chromium V8 Out-of-Bounds Read and Write Vulnerability
- CVE-2026-5281: Google Dawn Use-After-Free Vulnerability