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Fencer Vulns
critical 10.0

CVE-2020-12388 json

The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape.

published 2020-05-26 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4700

cvss
10.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.5%
EPSS 3.5% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

The Firefox content processes did not sufficiently lockdown access control which could result in a sandbox escape. *Note: this issue only affects Firefox on Windows operating systems.*. This vulnerability affects Firefox ESR < 68.8 and Firefox < 76.

Patch / fix

  • Mozilla Firefox ESR 68.8
  • Mozilla Firefox 76
  • MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +16 more 68.8.0-109.119.1
  • MozillaFirefox SLE Module for Desktop Applications 15 SP1 68.8.0-3.87.1
  • MozillaFirefox SLES 11 SP4-LTSS 68.8.0-78.73.1

suse advisories SUSE-SU-2020:14359-1SUSE-SU-2020:1218-1SUSE-SU-2020:1209-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 92.0-1.2
  • MozillaFirefox openSUSE Leap 15.1 68.8.0-lp151.2.45.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2020:0621-1

  • firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 76.0-r0
  • mozjs68 Alpine 3.12 68.8.0-r0
  • librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 76.0-r0
  • firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +10 more 68.8.0-r0

alpine advisories ALPINE-CVE-2020-12388

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

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-2020-12388 updated cvss 10.0

Mozilla: Sandbox escape with improperly guarded Access Tokens

  • Red Hat Enterprise Linux 5 firefox
    affected: no fix planned “Out of support scope”
  • 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

3.52% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 ESR
  • Mozilla Firefox

Classification

Weakness
  • CWE-20 Improper Input Validation

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.