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Fencer Vulns
critical 9.8

CVE-2020-6826 json

Mozilla developers Tyson Smith, Bob Clary, and Alexandru Michis reported memory safety bugs present in Firefox 74.

published 2020-04-24 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-27970

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 73%
public exploits
0
none known

Summary

Mozilla developers Tyson Smith, Bob Clary, and Alexandru Michis reported memory safety bugs present in Firefox 74. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 75.

Patch / fix

  • Mozilla Firefox 75
  • firefox Ubuntu 16.04 LTS 75.0+build3-0ubuntu0.16.04.1
  • firefox Ubuntu 18.04 LTS 75.0+build3-0ubuntu0.18.04.1
  • firefox Ubuntu 20.04 LTS 75.0+build3-0ubuntu1

ubuntu advisories UBUNTU-CVE-2020-6826

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

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 75.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 75.0-r0

alpine advisories ALPINE-CVE-2020-6826

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox Arch Linux 75.0-1

arch linux advisories AVG-1127

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-6826 updated cvss 9.8

Mozilla: Memory safety bugs fixed in Firefox 75

  • Red Hat Enterprise Linux 5 firefox Red Hat Enterprise Linux 6 firefox Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 firefox
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.43% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/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

References

Sources

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.