# CVE-2020-15667: Firefox ESR and 1 other: When processing a MAR update file, after the signature has been validated, an invalid name length could…

CVE-2020-15667 is fixed in Mozilla Firefox ESR (en-US) on 1 platform by Mozilla Firefox ESR (en-US) 91.0 (version 91.0), released August 4, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2020-15667
- Priority: High
- CVSS: 8.8
- EPSS: 0.0165
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 1, 2020
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-15667

## Description

When processing a MAR update file, after the signature has been validated, an invalid name length could result in a heap overflow, leading to memory corruption and potentially arbitrary code execution. Within Firefox as released by Mozilla, this issue is only exploitable with the Mozilla-controlled signing key. This vulnerability affects Firefox < 80.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Mozilla Firefox ESR (en-US) | 91.0 | [Mozilla Firefox ESR (en-US) 91.0](https://patchblox.com/security/data/fix/windows-app/mozilla.firefox.esr-91.0.md) | Aug 4, 2021 |

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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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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