CVE-2021-30533

Exp

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.

Published: 2021-06-07 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-30533 is rated Critical Active Threat (84.7/100): CVSS Medium severity, with high exploitation likelihood (EPSS 16.61%, 97th percentile). CISA KEV confirms active exploitation (added 2022-06-27) affecting Google / Chromium PopupBlocker. a weakness (CWE-863) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2021-30533

Name: Google Chromium PopupBlocker Security Bypass Vulnerability · CISA KEV detail

Exploit added: 2022-06-27

Action due: 2022-07-18

Required action: Apply updates per vendor instructions.

Public exploit references (Exploit-DB) for CVE-2021-30533

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-30533

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 16.71% 16.61% -0.10%
2 2026-05-26 10.53% 16.71% +6.18%
3 2025-11-21 — 10.53% —

Full EPSS history (35 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-30533

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-30533

OS Trackers for CVE-2021-30533

vendor priority summary link
alpine — CVE-2021-30533: 2 source package rows (chromium, qt5-qtwebengine); 14 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 14, open 0. https://security.alpinelinux.org/vuln/CVE-2021-30533
debian not yet assigned CVE-2021-30533 not yet assigned priority: Debian including 1 source packages (chromium), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-30533
gentoo high CVE-2021-30533: 1 GLSA(s) (202107-06), 2 atom(s) (www-client/chromium, www-client/google-chrome); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-30533
ubuntu medium CVE-2021-30533 medium priority: Ubuntu including 1 source packages (chromium-browser), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 4, DNE 2, released 2, ignored 1. https://ubuntu.com/security/CVE-2021-30533

Affected software / configurations for CVE-2021-30533

Vendor Product Version Raw CPE
google chrome < 91.0.4472.77 cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

References for CVE-2021-30533

cvelogic Threat Intelligence