What is CVE-2021-30533?

CVE-2021-30533 is a medium-severity vulnerability in Google Chrome, classified under Incorrect Authorization. CVSS score: 6.5/10. Published 2021-06-07.

How severe is CVE-2021-30533?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Is CVE-2021-30533 known to be exploited?

Yes. CVE-2021-30533 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-06-27), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.

Auth bypass in Google Chrome

CVE-2021-30533

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.

Vulnerability class: Broken Access Control

Published 2021-06-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.167 (97.0th percentile), scored 2026-10-18.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 97.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.166 · newest: 0.167 · change: +0.001

Affected products

Google Chrome — versions unspecified
Fedoraproject Fedora — versions 33, 34

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-06-27. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-07-18.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html (Release Notes, Vendor Advisory)
crbug.com/1145553 (Exploit, Patch, Issue Tracking, Vendor Advisory)
security.gentoo.org/glsa/202107-06 (vendor-advisory, Third Party Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory, Mailing List, Release Notes)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory, Mailing List, Release Notes)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-30533?: CVE-2021-30533 is a medium-severity vulnerability in Google Chrome, classified under Incorrect Authorization. CVSS score: 6.5/10. Published 2021-06-07.
How severe is CVE-2021-30533?: Medium severity. CVSS v3 base score is 6.5 out of 10.
Is CVE-2021-30533 known to be exploited?: Yes. CVE-2021-30533 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-06-27), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.