# CVE-2021-29967: Firefox ESR and 3 others: Mozilla developers reported memory safety bugs present in Firefox 88 and Firefox ESR 78.11.

CVE-2021-29967 is fixed in 11 products on 2 platforms, first by Mozilla Thunderbird (en-US) 78.11.0, released May 28, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-29967
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0137
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 1, 2021
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-29967

## Description

Mozilla developers reported memory safety bugs present in Firefox 88 and Firefox ESR 78.11. 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 Thunderbird < 78.11, Firefox < 89, and Firefox ESR < 78.11.

## 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 |
| Windows apps | Mozilla Thunderbird (en-US) | 78.11.0 | [Mozilla Thunderbird (en-US) 78.11.0](https://patchblox.com/security/data/fix/windows-app/mozilla.thunderbird-78.11.0.md) | May 28, 2021 |
| Linux | firefox RHEL 8 | 0:78.11.0-3.el8_4 | [RHSA-2021:2233](https://patchblox.com/security/data/fix/linux/rhsa-2021-2233.md) | Jun 3, 2021 |
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 89.0+build2-0ubuntu0.18.04.2 | [firefox 89.0+build2-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-89.0-build2-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | firefox Ubuntu 20.04 LTS (focal) | 89.0+build2-0ubuntu0.20.04.2 | [firefox 89.0+build2-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-89.0-build2-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | firefox ol 8 | 0:78.11.0-3.0.1.el8_4 | [ELSA-2021-2233](https://patchblox.com/security/data/fix/linux/elsa-2021-2233.md) | Jun 4, 2021 |
| Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 89.0+build2-0ubuntu0.18.04.2 | [firefox-geckodriver 89.0+build2-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-89.0-build2-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 89.0+build2-0ubuntu0.20.04.2 | [firefox-geckodriver 89.0+build2-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-89.0-build2-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 89.0+build2-0ubuntu0.18.04.2 | [firefox-mozsymbols 89.0+build2-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-89.0-build2-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 89.0+build2-0ubuntu0.20.04.2 | [firefox-mozsymbols 89.0+build2-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-89.0-build2-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird RHEL 8 | 0:78.11.0-1.el8_4 | [RHSA-2021:2264](https://patchblox.com/security/data/fix/linux/rhsa-2021-2264.md) | Jun 7, 2021 |
| Linux | thunderbird Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [thunderbird 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [thunderbird 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird ol 8 | 0:78.11.0-1.0.1.el8_4 | [ELSA-2021-2264](https://patchblox.com/security/data/fix/linux/elsa-2021-2264.md) | Jun 8, 2021 |
| Linux | thunderbird-gnome-support Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [thunderbird-gnome-support 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird-gnome-support Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [thunderbird-gnome-support 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [thunderbird-mozsymbols 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | thunderbird-mozsymbols Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [thunderbird-mozsymbols 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-calendar-timezones Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [xul-ext-calendar-timezones 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-calendar-timezones Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [xul-ext-calendar-timezones 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-gdata-provider Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [xul-ext-gdata-provider 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-gdata-provider Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [xul-ext-gdata-provider 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-lightning Ubuntu 18.04.6 LTS (bionic) | 1:78.11.0+build1-0ubuntu0.18.04.2 | [xul-ext-lightning 1:78.11.0+build1-0ubuntu0.18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-lightning-1-78.11.0-build1-0ubuntu0.18.04.2.md) | Jun 1, 2021 |
| Linux | xul-ext-lightning Ubuntu 20.04 LTS (focal) | 1:78.11.0+build1-0ubuntu0.20.04.2 | [xul-ext-lightning 1:78.11.0+build1-0ubuntu0.20.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-lightning-1-78.11.0-build1-0ubuntu0.20.04.2.md) | Jun 1, 2021 |

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