# CVE-2021-30533: Google Chromium PopupBlocker Security Bypass

> Remote attackers can bypass navigation restrictions in Google Chrome via crafted iframes due to insufficient popup blocker policy enforcement.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Yes, since 27 Jun 2022 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 7 Jun 2021
- **Updated:** 21 Oct 2025
- **Also known as:** CLEANSTART-2024-DN70918, DEBIAN-CVE-2021-30533, GHSA-83cg-29pr-h246, UBUNTU-CVE-2021-30533

## What is CVE-2021-30533?

CVE-2021-30533 is a medium-severity vulnerability in Fedoraproject Fedora, published on 7 Jun 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2021-30533?

It affects 2 products.


Products: Fedoraproject Fedora, Google Chrome.

## How do I fix CVE-2021-30533?

Upgrade to a fixed version. US federal agencies must fix it by 18 Jul 2022.

## Is CVE-2021-30533 being exploited?

Yes. Attackers have exploited CVE-2021-30533 in the wild since at least 27 Jun 2022.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-30533 and fix it if it is affected.

What it is: CVE-2021-30533 is a medium-severity vulnerability in Fedoraproject Fedora, published on 7 Jun 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: Yes. Attackers have exploited CVE-2021-30533 in the wild since at least 27 Jun 2022.

Affected product: Fedoraproject Fedora. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-30533/ (Markdown: https://insights.sbomify.com/CVE-2021-30533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-30533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-30533
- OSV: https://osv.dev/vulnerability/CVE-2021-30533

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-30533/
Summaries are generated and may contain mistakes; the official description above is the record.