# CVE-2017-7813: firefox: Inside the JavaScript parser, a cast of an integer to a narrower type can result in data read from outside the buffer...

CVE-2017-7813 is fixed in 4 products on 1 platform, first by firefox 56.0+build6-0ubuntu1, released October 1, 2017. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2017-7813
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0156
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 1, 2017

## Description

Inside the JavaScript parser, a cast of an integer to a narrower type can result in data read from outside the buffer being parsed. This usually results in a non-exploitable crash, but can leak a limited amount of information from memory if it matches JavaScript identifier syntax. This vulnerability affects Firefox < 56.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | firefox Ubuntu 18.04.6 LTS (bionic) | 56.0+build6-0ubuntu1 | [firefox 56.0+build6-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-56.0-build6-0ubuntu1.md) | Oct 1, 2017 |
| Linux | firefox-globalmenu Ubuntu 18.04.6 LTS (bionic) | 56.0+build6-0ubuntu1 | [firefox-globalmenu 56.0+build6-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-globalmenu-56.0-build6-0ubuntu1.md) | Oct 1, 2017 |
| Linux | firefox-mozsymbols Ubuntu 18.04.6 LTS (bionic) | 56.0+build6-0ubuntu1 | [firefox-mozsymbols 56.0+build6-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-mozsymbols-56.0-build6-0ubuntu1.md) | Oct 1, 2017 |
| Linux | firefox-testsuite Ubuntu 18.04.6 LTS (bionic) | 56.0+build6-0ubuntu1 | [firefox-testsuite 56.0+build6-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-firefox-testsuite-56.0-build6-0ubuntu1.md) | Oct 1, 2017 |

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Data as of 2026-11-07T12:40:37Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo