CVE-2019-9801: Input Validation

Published Mar 19, 2019
·
Updated

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.

Other sources

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.

Affected Software

11 affected componentsFixes available
Mozilla Firefox<66
66
Mozilla Thunderbird<60.6
60.6
Mozilla Firefox ESR<60.6
60.6
All of the following
Any of the following
Mozilla Firefox<66.0
Mozilla Firefox ESR<60.6
Mozilla Thunderbird<60.6
Microsoft Windows
Mozilla Firefox<66.0
Mozilla Firefox ESR<60.6
Mozilla Thunderbird<60.6
Microsoft Windows

Event History

Mar 19, 2019
CVE Published
via Mozilla·12:00 AM
Apr 26, 2019
CVE Published
via MITRE·04:13 PM
Data Sourced
via MITRE·04:13 PM
DescriptionWeakness
Data Sourced
via NVD·05:29 PM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is CVE-2019-9801?

CVE-2019-9801 is a vulnerability in Firefox and Thunderbird that allows any registered Program ID to be accepted as an external protocol handler on Windows operating systems.

2

How does CVE-2019-9801 affect Mozilla Firefox?

Mozilla Firefox versions up to and including 66 are affected by CVE-2019-9801.

3

How does CVE-2019-9801 affect Mozilla Thunderbird?

Mozilla Thunderbird versions up to and including 60.6 are affected by CVE-2019-9801.

4

What is the severity of CVE-2019-9801?

CVE-2019-9801 has a severity rating of 5.3 (Medium).

5

How can I mitigate the vulnerability?

Update Mozilla Firefox to version 66 or later, or update Mozilla Thunderbird to version 60.6 or later to mitigate CVE-2019-9801.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203
CVE-2019-9801 - Input Validation - SecAlerts