CVE-2021-30533Known exploitationNetwork attack vector

Navigation restriction bypass via crafted iframe

Published Jun 7, 2021 · Updated Oct 21, 2025

Insufficient policy enforcement in Google Chrome before 91.0.4472.77 allows remote attackers to bypass navigation restrictions via a crafted iframe. PopupBlocker fails to enforce its navigation policy on requests initiated through the iframe; public records identify no more specific code-level locus. Exploitation requires a user to load attacker-controlled web content, and the documented consequence is unauthorized navigation rather than data disclosure or code execution.

CVSS severity6.5
Medium
EPSS probability16.61%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient policy enforcement in Google Chrome before 91.0.4472.77 allows remote attackers to bypass navigation restrictions via a crafted iframe. PopupBlocker fails to enforce its navigation policy on requests initiated through the iframe; public records identify no more specific code-level locus. Exploitation requires a user to load attacker-controlled web content, and the documented consequence is unauthorized navigation rather than data disclosure or code execution.

The record

CVE
CVE-2021-30533
Published
Jun 7, 2021
Updated
Oct 21, 2025
Vendor
Google Cloud
Product
Google Chrome
Classifications
CWE-863, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <91.0.4472.77

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Google Chromeversion=unspecified <91.0.4472.77

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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