CVE-2019-11753
The Firefox installer allows Firefox to be installed to a custom user writable location, leaving it unprotected from manipulation by unprivileged users or malware.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.23% probability · 13th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-354
- Affected
- mozilla/firefox · mozilla/firefox esr
- Source
- security@mozilla.org
EPSS 0.2% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html
- https://bugzilla.mozilla.org/show_bug.cgi?id=1574980Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-25/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-26/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-27/Vendor Advisory
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html
- http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html
- https://bugzilla.mozilla.org/show_bug.cgi?id=1574980Issue Tracking, Permissions Required, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-25/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-26/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-27/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.