What is CVE-2019-11736?

CVE-2019-11736 is a high-severity vulnerability in Microsoft Windows, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 7.0/10. Published 2019-09-27.

How severe is CVE-2019-11736?

High severity. CVSS v3 base score is 7.0 out of 10.

Vulnerability in Microsoft Windows

CVE-2019-11736

The Mozilla Maintenance Service does not guard against files being hardlinked to another file in the updates directory, allowing for the replacement of local files, including the Maintenance Service executable, which is run with privileged access. Additionally, there was a race condition during checks for junctions and symbolic links by the Maintenance Service, allowing for potential local file and directory manipulation to be undetected in some circumstances. This allows for potential privilege escalation by a user with unprivileged local access. <br>*Note: These attacks requires local system access and only affects Windows. Other operating systems are not affected.*. This vulnerability affects Firefox < 69 and Firefox ESR < 68.1.

Vulnerability class: Race Condition

Published 2019-09-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.0 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (10.1th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 10th percentile — 10.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Microsoft Windows
Mozilla Firefox — versions unspecified
Mozilla Firefox Esr — versions unspecified
Mozilla Firefox Esr

Weakness classification (CWE)

CWE-362 — Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)

References

bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)
bugzilla.mozilla.org/show_bug.cgi (Permissions Required, Issue Tracking, Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2019-25/ (Vendor Advisory)
www.mozilla.org/security/advisories/mfsa2019-26/ (Vendor Advisory)
lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html (vendor-advisory)
lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html (vendor-advisory)

Frequently asked questions

What is CVE-2019-11736?: CVE-2019-11736 is a high-severity vulnerability in Microsoft Windows, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 7.0/10. Published 2019-09-27.
How severe is CVE-2019-11736?: High severity. CVSS v3 base score is 7.0 out of 10.