CVE-2019-9801

Name: CVE-2019-9801
Creator: NVD / NIST
Published: 2019-04-26T17:29:02.977+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 1.31%

Last modified Jun 17, 2026

CVE-2019-9801 is a vulnerability of currently unknown severity. Firefox will accept any registered Program ID as an external protocol handler and offer to launch this local application when given a matching URL on Windows operating systems. This should only happen if the program has specifically registered itself as a "URL Handler" in the Windows registry. EPSS estimates a 1.31% chance of exploitation in the next 30 days.

Description

Firefox will accept any registered Program ID as an external protocol handler and offer to launch this local application when given a matching URL on Windows operating systems. This should only happen if the program has specifically registered itself as a "URL Handler" in the Windows registry. *Note: This issue only affects Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

Metrics

EPSS Probability

1.31%

67.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 66.0
Mozilla	Firefox Esr	< 60.6
Mozilla	Thunderbird	< 60.6

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1527717Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1527717Issue Tracking, Permissions Required, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory

Timeline

Published: Apr 26, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-9801?

How severe is CVE-2019-9801?

Severity scoring for CVE-2019-9801 is pending analysis. The EPSS model estimates a 1.31% probability of exploitation in the next 30 days.

How do I fix CVE-2019-9801?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-9801?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST