CVE-2019-9788: Critical severity Mozilla Firefox vulnerability
Last updated 25 August 2025
Other sources
Mozilla developers and community members Bob Clary, Chun-Min Chang, Aral Yaman, Andreea Pavel, Jonathan Kew, Gary Kwong, Alex Gaynor, Masayuki Nakano, and Anne van Kesteren reported memory safety bugs present in Firefox 65 and Firefox ESR 60.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code.
Mozilla developers and community members Bob Clary, Chun-Min Chang, Aral Yaman, Andreea Pavel, Jonathan Kew, Gary Kwong, Alex Gaynor, Masayuki Nakano, and Anne van Kesteren reported memory safety bugs present in Firefox 65, Firefox ESR 60.5, and Thunderbird 60.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code.
— Mozilla
Mozilla developers and community members reported memory safety bugs present in Firefox 65 and Firefox ESR 60.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code.
External Reference:
https://www.mozilla.org/en-US/security/advisories/mfsa2019-08/#CVE-2019-9788
— Red Hat
Mozilla developers and community members reported memory safety bugs present in Firefox 65, Firefox ESR 60.5, and Thunderbird 60.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
— Launchpad
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Firefoxto a version that resolves this vulnerability.Fixed in 66 - Upgrade
Upgrade
Thunderbirdto a version that resolves this vulnerability.Fixed in 60.6 - Upgrade
Upgrade
Firefox ESRto a version that resolves this vulnerability.Fixed in 60.6 - Upgrade
Upgrade
debian/firefoxto a version that resolves this vulnerability.Fixed in 152.0.1-1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 115.14.0esr-1~deb11u1Fixed in 140.12.0esr-1~deb11u1Fixed in 140.10.2esr-1~deb12u1Fixed in 140.12.0esr-1~deb12u1Fixed in 140.10.2esr-1~deb13u1Fixed in 140.12.0esr-1~deb13u1Fixed in 140.11.0esr-1Fixed in 140.12.0esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:115.12.0-1~deb11u1Fixed in 1:140.12.0esr-1~deb11u1Fixed in 1:140.10.1esr-1~deb12u1Fixed in 1:140.12.0esr-1~deb12u1Fixed in 1:140.10.1esr-1~deb13u1Fixed in 1:140.12.0esr-1~deb13u1Fixed in 1:140.11.0esr-1Fixed in 1:140.12.0esr-1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 115.14.0esr-1~deb11u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.12.0esr-1~deb11u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.10.2esr-1~deb12u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.12.0esr-1~deb12u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.10.2esr-1~deb13u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.12.0esr-1~deb13u1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.11.0esr-1 - Upgrade
Upgrade
debian/firefox-esrto a version that resolves this vulnerability.Fixed in 140.12.0esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:115.12.0-1~deb11u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1~deb11u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.10.1esr-1~deb12u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1~deb12u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.10.1esr-1~deb13u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1~deb13u1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.11.0esr-1 - Upgrade
Upgrade
debian/thunderbirdto a version that resolves this vulnerability.Fixed in 1:140.12.0esr-1
Event History
Parent advisories
This vulnerability appears in the following advisories.
Peer vulnerabilities
Found alongside the following vulnerabilities.
Frequently Asked Questions
What is the vulnerability ID of this security issue?
The vulnerability ID of this security issue is CVE-2019-9788.
What is the severity level of CVE-2019-9788?
CVE-2019-9788 has a severity level of critical.
Which versions of Firefox are affected by CVE-2019-9788?
Firefox versions up to and exclusive of 66.0 are affected by CVE-2019-9788.
How can I fix the vulnerability in Firefox?
To fix the vulnerability in Firefox, update to version 66.0 or higher.
Where can I find more information about CVE-2019-9788?
You can find more information about CVE-2019-9788 in the references provided: [link1](https://bugzilla.mozilla.org/buglist.cgi?bug_id=1518001%2C1521304%2C1521214%2C1506665%2C1516834%2C1518774%2C1524755%2C1523362%2C1524214%2C1529203) and [link2](https://www.mozilla.org/en-US/security/advisories/mfsa2019-07/).