# CVE-2021-38493: Mozilla Firefox ESR and 3 others: Mozilla developers reported memory safety bugs present in Firefox 91 and Firefox ESR 78.13.

CVE-2021-38493 is fixed in 11 products on 2 platforms, first by Mozilla Thunderbird (en-US) 91.0.3, released August 24, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-38493
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0125
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 8, 2021
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-38493

## Description

Mozilla developers reported memory safety bugs present in Firefox 91 and Firefox ESR 78.13. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox ESR < 78.14, Thunderbird < 78.14, and Firefox < 92.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Mozilla Firefox ESR (en-US) | 102.0 | [Mozilla Firefox ESR (en-US) 102.0](https://patchblox.com/security/data/fix/windows-app/mozilla.firefox.esr-102.0.md) | Jun 23, 2022 |
| Windows apps | Mozilla Thunderbird (en-US) | 91.0.3 | [Mozilla Thunderbird (en-US) 91.0.3](https://patchblox.com/security/data/fix/windows-app/mozilla.thunderbird-91.0.3.md) | Aug 24, 2021 |
| Linux | firefox RHEL 8 | 0:78.14.0-1.el8_4 | [RHSA-2021:3497](https://patchblox.com/security/data/fix/linux/rhsa-2021-3497.md) | Sep 13, 2021 |
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 92.0+build3-0ubuntu0.18.04.1 | [firefox 92.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-92.0-build3-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | firefox Ubuntu 20.04 LTS (focal) | 92.0+build3-0ubuntu0.20.04.1 | [firefox 92.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-92.0-build3-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | firefox ol 8 | 0:78.14.0-1.0.1.el8_4 | [ELSA-2021-3497](https://patchblox.com/security/data/fix/linux/elsa-2021-3497.md) | Sep 13, 2021 |
| Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 92.0+build3-0ubuntu0.18.04.1 | [firefox-geckodriver 92.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-92.0-build3-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 92.0+build3-0ubuntu0.20.04.1 | [firefox-geckodriver 92.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-92.0-build3-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 92.0+build3-0ubuntu0.18.04.1 | [firefox-mozsymbols 92.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-92.0-build3-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 92.0+build3-0ubuntu0.20.04.1 | [firefox-mozsymbols 92.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-92.0-build3-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird RHEL 8 | 0:78.14.0-1.el8_4 | [RHSA-2021:3499](https://patchblox.com/security/data/fix/linux/rhsa-2021-3499.md) | Sep 13, 2021 |
| Linux | thunderbird Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [thunderbird 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [thunderbird 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird ol 8 | 0:78.14.0-1.0.1.el8_4 | [ELSA-2021-3499](https://patchblox.com/security/data/fix/linux/elsa-2021-3499.md) | Sep 13, 2021 |
| Linux | thunderbird-gnome-support Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [thunderbird-gnome-support 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird-gnome-support Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [thunderbird-gnome-support 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [thunderbird-mozsymbols 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | thunderbird-mozsymbols Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [thunderbird-mozsymbols 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-calendar-timezones Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [xul-ext-calendar-timezones 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-calendar-timezones Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [xul-ext-calendar-timezones 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-gdata-provider Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [xul-ext-gdata-provider 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-gdata-provider Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [xul-ext-gdata-provider 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-lightning Ubuntu 18.04.6 LTS (bionic) | 1:78.14.0+build1-0ubuntu0.18.04.1 | [xul-ext-lightning 1:78.14.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-lightning-1-78.14.0-build1-0ubuntu0.18.04.1.md) | Sep 8, 2021 |
| Linux | xul-ext-lightning Ubuntu 20.04 LTS (focal) | 1:78.14.0+build1-0ubuntu0.20.04.1 | [xul-ext-lightning 1:78.14.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-lightning-1-78.14.0-build1-0ubuntu0.20.04.1.md) | Sep 8, 2021 |

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