# CVE-2020-12389: Firefox ESR: The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox…

CVE-2020-12389 is fixed in Mozilla Firefox ESR (en-US) on 1 platform by Mozilla Firefox ESR (en-US) 78.0esr (version 78.0esr), released June 25, 2020. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2020-12389
- Priority: Urgent
- CVSS: 10.0
- EPSS: 0.0172
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 26, 2020
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-12389

## Description

The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.

## 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 |

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Data as of 2026-11-08T13:06:02Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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