# CVE-2020-6799: Firefox ESR: Command line arguments could have been injected during Firefox invocation as a shell handler for certain…

CVE-2020-6799 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: High.

- Web page: https://patchblox.com/security/cve/CVE-2020-6799
- Priority: High
- CVSS: 8.8
- EPSS: 0.0153
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 2, 2020
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-6799

## Description

Command line arguments could have been injected during Firefox invocation as a shell handler for certain unsupported file types. This required Firefox to be configured as the default handler for a given file type and for a file downloaded to be opened in a third party application that insufficiently sanitized URL data. In that situation, clicking a link in the third party application could have been used to retrieve and execute files whose location was supplied through command line arguments. Note: This issue only affects Windows operating systems and when Firefox is configured as the default handler for non-default filetypes. Other operating systems are unaffected. This vulnerability affects Firefox < 73 and Firefox < ESR68.5.

## 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 2026-11-08T00:53:09Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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