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CVE-2021-30533

MEDIUM
6.5
CVSS Score
Published: June 7, 2021 at 07:25 PM UTC
Updated: June 17, 2026 at 03:50 AM UTC
2 products affected across 2 vendorsChromeFedora

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Severity
MEDIUM6.5
Exploitation
CISA KEV
Exploit prediction
EPSS 17%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score16.7%

EPSS (Exploit Prediction Scoring System) estimates a 16.7% chance this CVE is exploited in the wild within the next 30 days — higher than 97% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Unknown
Added to KEV
Jun 27, 2022
Remediation Due
Jul 18, 2022
1567 days overdue
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-30533

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Fedora· Fedora Projectrpm
95%
3334
Chrome· Googlenpm
95%
v < 91.0.4472.77
Affected range stops below 91.0.4472.77, so it looks safe — our inference, not a vendor statement

References (6)

x_refsource_MISCRelease NotesVendor Advisory
Source: [email protected]
https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
x_refsource_MISCExploitIssue TrackingPatchVendor Advisory
Source: [email protected]
https://crbug.com/1145553
Vendor Advisoryx_refsource_FEDORAMailing ListRelease Notes
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
Vendor Advisoryx_refsource_FEDORAMailing ListRelease Notes
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202107-06
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30533

SSVC — Action Prioritization

SSVCActiveNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-863

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