# CVE-2021-38504: Mozilla Firefox ESR and 3 others: When interacting with an HTML input element's file picker dialog with webkitdirectory set, a use-after-free…

CVE-2021-38504 is fixed in 12 products on 2 platforms, first by Mozilla Thunderbird (en-US) 91.3.0, released November 1, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-38504
- Priority: High
- CVSS: 9.8 (Important)
- EPSS: 0.0177
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 2, 2021
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-38504

## Description

When interacting with an HTML input element's file picker dialog with webkitdirectory set, a use-after-free could have resulted, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

## 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) | 91.3.0 | [Mozilla Thunderbird (en-US) 91.3.0](https://patchblox.com/security/data/fix/windows-app/mozilla.thunderbird-91.3.0.md) | Nov 1, 2021 |
| Linux | firefox RHEL 8 | 0:91.3.0-1.el8_4 | [RHSA-2021:4123](https://patchblox.com/security/data/fix/linux/rhsa-2021-4123.md) | Nov 3, 2021 |
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | [firefox 94.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-94.0-build3-0ubuntu0.18.04.1.md) | Nov 2, 2021 |
| Linux | firefox Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | [firefox 94.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-94.0-build3-0ubuntu0.20.04.1.md) | Nov 2, 2021 |
| Linux | firefox Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | [firefox 94.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-firefox-94.0-build3-0ubuntu1.md) | Nov 2, 2021 |
| Linux | firefox ol 8 | 0:91.3.0-1.0.1.el8_4 | [ELSA-2021-4123](https://patchblox.com/security/data/fix/linux/elsa-2021-4123.md) | Nov 4, 2021 |
| Linux | firefox-esr Debian 12.15 (bookworm) | 91.3.0esr-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | firefox-esr Debian 13.5 (trixie) | 91.3.0esr-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | firefox-esr Debian 14 | 91.3.0esr-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | [firefox-geckodriver 94.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-94.0-build3-0ubuntu0.18.04.1.md) | Nov 2, 2021 |
| Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | [firefox-geckodriver 94.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-94.0-build3-0ubuntu0.20.04.1.md) | Nov 2, 2021 |
| Linux | firefox-geckodriver Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | [firefox-geckodriver 94.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-firefox-geckodriver-94.0-build3-0ubuntu1.md) | Nov 2, 2021 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 94.0+build3-0ubuntu0.18.04.1 | [firefox-mozsymbols 94.0+build3-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-94.0-build3-0ubuntu0.18.04.1.md) | Nov 2, 2021 |
| Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 94.0+build3-0ubuntu0.20.04.1 | [firefox-mozsymbols 94.0+build3-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-94.0-build3-0ubuntu0.20.04.1.md) | Nov 2, 2021 |
| Linux | firefox-mozsymbols Ubuntu 22.04.1 LTS (jammy) | 94.0+build3-0ubuntu1 | [firefox-mozsymbols 94.0+build3-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-firefox-mozsymbols-94.0-build3-0ubuntu1.md) | Nov 2, 2021 |
| Linux | thunderbird Debian 12.15 (bookworm) | 1:91.3.0-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | thunderbird Debian 13.5 (trixie) | 1:91.3.0-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | thunderbird Debian 14 | 1:91.3.0-1 | [DEBIAN-CVE-2021-38504](https://patchblox.com/security/data/fix/linux/debian-cve-2021-38504.md) | Dec 8, 2021 |
| Linux | thunderbird RHEL 8 | 0:91.3.0-2.el8_4 | [RHSA-2021:4130](https://patchblox.com/security/data/fix/linux/rhsa-2021-4130.md) | Nov 4, 2021 |
| Linux | thunderbird Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [thunderbird 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [thunderbird 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [thunderbird 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-thunderbird-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |
| Linux | thunderbird ol 8 | 0:91.3.0-2.0.1.el8_4 | [ELSA-2021-4130](https://patchblox.com/security/data/fix/linux/elsa-2021-4130.md) | Nov 5, 2021 |
| Linux | thunderbird-gnome-support Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-gnome-support-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird-gnome-support Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [thunderbird-gnome-support 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-gnome-support-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird-gnome-support Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [thunderbird-gnome-support 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-thunderbird-gnome-support-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |
| Linux | thunderbird-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-thunderbird-mozsymbols-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird-mozsymbols Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [thunderbird-mozsymbols 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-thunderbird-mozsymbols-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | thunderbird-mozsymbols Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [thunderbird-mozsymbols 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-thunderbird-mozsymbols-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |
| Linux | xul-ext-calendar-timezones Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-calendar-timezones-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-calendar-timezones Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [xul-ext-calendar-timezones 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-calendar-timezones-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-calendar-timezones Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [xul-ext-calendar-timezones 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-xul-ext-calendar-timezones-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |
| Linux | xul-ext-gdata-provider Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-gdata-provider-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-gdata-provider Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [xul-ext-gdata-provider 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-gdata-provider-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-gdata-provider Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [xul-ext-gdata-provider 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-xul-ext-gdata-provider-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |
| Linux | xul-ext-lightning Ubuntu 18.04.6 LTS (bionic) | 1:91.5.0+build1-0ubuntu0.18.04.1 | [xul-ext-lightning 1:91.5.0+build1-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-xul-ext-lightning-1-91.5.0-build1-0ubuntu0.18.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-lightning Ubuntu 20.04 LTS (focal) | 1:91.5.0+build1-0ubuntu0.20.04.1 | [xul-ext-lightning 1:91.5.0+build1-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-xul-ext-lightning-1-91.5.0-build1-0ubuntu0.20.04.1.md) | Feb 16, 2023 |
| Linux | xul-ext-lightning Ubuntu 22.04.1 LTS (jammy) | 1:91.3.1+build1-0ubuntu1 | [xul-ext-lightning 1:91.3.1+build1-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-xul-ext-lightning-1-91.3.1-build1-0ubuntu1.md) | Nov 2, 2021 |

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