# CVE-2020-6810: Firefox ESR: After a website had entered fullscreen mode, it could have used a previously opened popup to obscure…

CVE-2020-6810 is fixed in 4 products on 2 platforms, first by firefox 74.0+build3-0ubuntu0.18.04.1, released March 10, 2020. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2020-6810
- Priority: Routine
- CVSS: 4.3 (Medium)
- EPSS: 0.0103
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 10, 2020
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-6810

## Description

After a website had entered fullscreen mode, it could have used a previously opened popup to obscure the notification that indicates the browser is in fullscreen mode. Combined with spoofing the browser chrome, this could have led to confusing the user about the current origin of the page and credential theft or other attacks. This vulnerability affects Firefox < 74.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Mozilla Firefox ESR (en-US) | 78.0esr | [Mozilla Firefox ESR (en-US) 78.0esr](https://patchblox.com/security/data/fix/windows-app/mozilla.firefox.esr-78.0esr.md) | Jun 25, 2020 |
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 74.0+build3-0ubuntu0.18.04.1 | [firefox 74.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-74.0-build3-0ubuntu0.18.04.1.md) | Mar 10, 2020 |
| Linux | firefox Ubuntu 20.04 LTS (focal) | 74.0+build3-0ubuntu1 | [firefox 74.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-74.0-build3-0ubuntu1.md) | Mar 10, 2020 |
| Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 74.0+build3-0ubuntu0.18.04.1 | [firefox-geckodriver 74.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-74.0-build3-0ubuntu0.18.04.1.md) | Mar 10, 2020 |
| Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 74.0+build3-0ubuntu1 | [firefox-geckodriver 74.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-74.0-build3-0ubuntu1.md) | Mar 10, 2020 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 74.0+build3-0ubuntu0.18.04.1 | [firefox-mozsymbols 74.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-74.0-build3-0ubuntu0.18.04.1.md) | Mar 10, 2020 |
| Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 74.0+build3-0ubuntu1 | [firefox-mozsymbols 74.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-74.0-build3-0ubuntu1.md) | Mar 10, 2020 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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