Mozilla developers and community members reported memory safety bugs present in Firefox 65.

published 2019-04-26 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-19151

cvss: 9.8; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 68%
public exploits: 0; none known

Mozilla developers and community members reported memory safety bugs present in Firefox 65. 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 Firefox < 66.

Patch / fix

fixed in 1 distros 3

Mozilla Firefox 66

ubuntu opensuse arch linux

firefox Ubuntu 14.04 LTS 66.0.1+build1-0ubuntu0.14.04.1
firefox Ubuntu 16.04 LTS 66.0+build3-0ubuntu0.16.04.2
firefox Ubuntu 18.04 LTS 66.0+build3-0ubuntu0.18.04.1

ubuntu advisories UBUNTU-CVE-2019-9789

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1

firefox Arch Linux 66.0-1

arch linux advisories AVG-925

Exploit prediction

1.21% chance of exploitation in the next 30 days, higher than 68% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.0	9.8	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

Mozilla Firefox

Classification

Weakness

CWE-787 Out-of-bounds Write

References

mozilla.org /security/advisories/mfsa2019-07/
vendor-advisory
bugzilla.mozilla.org /buglist.cgi?bug_id=1520483%2C1522987%2C1528199%2C1519337%2C1525549%2C1516179%2C1518524%2C1518331%2C1526579%2C
broken-link, issue-tracking, vendor-advisory

Sources

CVE List CVE-2019-9789
NVD CVE-2019-9789

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary