# CVE-2020-15681: Firefox ESR and 1 other: When multiple WASM threads had a reference to a module, and were looking up exported functions, one WASM…

CVE-2020-15681 is fixed in 4 products on 2 platforms, first by firefox 82.0+build2-0ubuntu0.18.04.1, released October 21, 2020. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2020-15681
- Priority: High
- CVSS: 7.5 (Medium)
- EPSS: 0.0109
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 21, 2020
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2020-15681

## Description

When multiple WASM threads had a reference to a module, and were looking up exported functions, one WASM thread could have overwritten another's entry in a shared stub table, resulting in a potentially exploitable crash. This vulnerability affects Firefox < 82.

## 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 |
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 82.0+build2-0ubuntu0.18.04.1 | [firefox 82.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-82.0-build2-0ubuntu0.18.04.1.md) | Oct 21, 2020 |
| Linux | firefox Ubuntu 20.04 LTS (focal) | 82.0+build2-0ubuntu0.20.04.1 | [firefox 82.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-82.0-build2-0ubuntu0.20.04.1.md) | Oct 21, 2020 |
| Linux | firefox-geckodriver Ubuntu 18.04.6 LTS (bionic) | 82.0+build2-0ubuntu0.18.04.1 | [firefox-geckodriver 82.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-geckodriver-82.0-build2-0ubuntu0.18.04.1.md) | Oct 21, 2020 |
| Linux | firefox-geckodriver Ubuntu 20.04 LTS (focal) | 82.0+build2-0ubuntu0.20.04.1 | [firefox-geckodriver 82.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-geckodriver-82.0-build2-0ubuntu0.20.04.1.md) | Oct 21, 2020 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 82.0+build2-0ubuntu0.18.04.1 | [firefox-mozsymbols 82.0+build2-0ubuntu0.18.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-82.0-build2-0ubuntu0.18.04.1.md) | Oct 21, 2020 |
| Linux | firefox-mozsymbols Ubuntu 20.04 LTS (focal) | 82.0+build2-0ubuntu0.20.04.1 | [firefox-mozsymbols 82.0+build2-0ubuntu0.20.04.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-firefox-mozsymbols-82.0-build2-0ubuntu0.20.04.1.md) | Oct 21, 2020 |

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