CVE-2020-6821 json
When reading from areas partially or fully outside the source resource with WebGL's <code>copyTexSubImage</code> method, the specification…
published 2020-04-24 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-27965
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.5%
- EPSS 1.5% chance of exploitation in 30 days, percentile 74%
- public exploits
- 0
- none known
Summary
When reading from areas partially or fully outside the source resource with WebGL's <code>copyTexSubImage</code> method, the specification requires the returned values be zero. Previously, this memory was uninitialized, leading to potentially sensitive data disclosure. This vulnerability affects Thunderbird < 68.7.0, Firefox ESR < 68.7, and Firefox < 75.
Patch / fix
- Mozilla Thunderbird 68.7.0
- Mozilla Firefox ESR 68.7
- Mozilla Firefox 75
- firefox-esr Debian 14, Debian 13, Debian 12 68.7.0esr-1
- thunderbird Debian 14, Debian 13, Debian 12 1:68.7.0-1
debian advisories DEBIAN-CVE-2020-6821
- 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
- thunderbird Ubuntu 16.04 LTS 1:68.7.0+build1-0ubuntu0.16.04.2
- thunderbird Ubuntu 18.04 LTS 1:68.7.0+build1-0ubuntu0.18.04.1
- thunderbird Ubuntu 20.04 LTS 1:68.7.0+build1-0ubuntu1
ubuntu advisories UBUNTU-CVE-2020-6821
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
- thunderbird RHEL 8 68.7.0-1.el8_1
- thunderbird RHEL 7 68.7.0-1.el7_8
- thunderbird RHEL 6 68.7.0-1.el6_10
- firefox RHEL 6 68.7.0-2.el6_10
- firefox RHEL 7 68.7.0-2.el7_8
- firefox RHEL 8 68.7.0-2.el8_1
- thunderbird RHEL 8.0 E4S 68.7.0-1.el8_0
- firefox RHEL 8.0 E4S 68.7.0-2.el8_0
red hat advisories RHSA-2020:1495RHSA-2020:1496RHSA-2020:1489RHSA-2020:1488RHSA-2020:1429RHSA-2020:1420
- MozillaThunderbird SLE Workstation Extension 15 SP1 68.7.0-3.77.1
- MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +16 more 68.7.0-109.116.1
- MozillaFirefox SLE Module for Desktop Applications 15 SP1 68.7.0-3.84.2
- MozillaFirefox SLES 11 SP4-LTSS 68.7.0-78.70.1
suse advisories SUSE-SU-2020:1027-1SUSE-SU-2020:0978-1SUSE-SU-2020:14339-1SUSE-SU-2020:0971-1
- firefox-esr openSUSE Tumbleweed 128.5.1-1.1
- MozillaFirefox openSUSE Tumbleweed 92.0-1.2
- MozillaThunderbird openSUSE Tumbleweed 91.1.1-1.1
- MozillaThunderbird openSUSE Leap 15.1 68.7.0-lp151.2.35.1
- MozillaThunderbird openSUSE Leap 15.1 68.7.0-lp151.2.31.1
- MozillaFirefox openSUSE Leap 15.1 68.7.0-lp151.2.42.1
opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10600-1openSUSE-SU-2024:10601-1openSUSE-SU-2020:0544-1openSUSE-SU-2020:0520-1openSUSE-SU-2020:0493-1
- firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 75.0-r0
- mozjs68 Alpine 3.12 68.7.0-r0
- librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 75.0-r0
- firefox-esr Alpine 3.23, Alpine 3.22, Alpine 3.21 +10 more 68.7.0-r0
- thunderbird Alpine 3.23, Alpine 3.22, Alpine 3.21 +5 more 68.7.0-r0
alpine advisories ALPINE-CVE-2020-6821
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-2020-6821 updated cvss 7.5
Mozilla: Uninitialized memory could be read when using the WebGL copyTexSubImage method
-
Red Hat Enterprise Linux 5 firefox, thunderbirdaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux AppStream (v. 8) firefox 68.7.0-2.el8_1, thunderbird 68.7.0-1.el8_1fixed: vendor fix RHSA-2020:1406
-
Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox 68.7.0-2.el8_0, thunderbird 68.7.0-1.el8_0fixed: vendor fix RHSA-2020:1404
-
Red Hat Enterprise Linux Client (v. 7) firefox 68.7.0-2.el7_8, thunderbird 68.7.0-1.el7_8 Red Hat Enterprise Linux Client Optional (v. 7) firefox 68.7.0-2.el7_8fixed: vendor fix RHSA-2020:1420
-
Red Hat Enterprise Linux Desktop (v. 6) firefox 68.7.0-2.el6_10, thunderbird 68.7.0-1.el6_10 Red Hat Enterprise Linux Desktop Optional (v. 6) firefox 68.7.0-2.el6_10 Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox 68.7.0-2.el6_10 Red Hat Enterprise Linux Server (v. 6) firefox 68.7.0-2.el6_10fixed: vendor fix RHSA-2020:1429
-
Red Hat Enterprise Linux Server (v. 7) firefox 68.7.0-2.el7_8fixed: vendor fix RHSA-2020:1420
-
Red Hat Enterprise Linux Server Optional (v. 6) firefox 68.7.0-2.el6_10, thunderbird 68.7.0-1.el6_10fixed: vendor fix RHSA-2020:1429
-
Red Hat Enterprise Linux Server Optional (v. 7) firefox 68.7.0-2.el7_8, thunderbird 68.7.0-1.el7_8fixed: vendor fix RHSA-2020:1420
show 4 moreshow fewer
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Red Hat Enterprise Linux Workstation (v. 6) firefox 68.7.0-2.el6_10, thunderbird 68.7.0-1.el6_10fixed: vendor fix RHSA-2020:1429
-
Red Hat Enterprise Linux Workstation (v. 7) firefox 68.7.0-2.el7_8, thunderbird 68.7.0-1.el7_8fixed: vendor fix RHSA-2020:1420
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Red Hat Enterprise Linux Workstation Optional (v. 6) firefox 68.7.0-2.el6_10fixed: vendor fix RHSA-2020:1429
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Red Hat Enterprise Linux Workstation Optional (v. 7) firefox 68.7.0-2.el7_8fixed: vendor fix RHSA-2020:1420
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
1.50% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:P/I:N/A:N |
Affected products
- Mozilla Thunderbird
- Mozilla Firefox ESR
- Mozilla Firefox
Classification
- Weakness
-
- CWE-908 Use of Uninitialized Resource
References
-
usn.ubuntu.com
/4335-1/
vendor-advisory, third-party-advisory
-
mozilla.org
/security/advisories/mfsa2020-13/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2020-12/
vendor-advisory
-
mozilla.org
/security/advisories/mfsa2020-14/
vendor-advisory
-
bugzilla.mozilla.org
/show_bug.cgi?id=1625404
issue-tracking, permissions-required
Sources
- CVE List CVE-2020-6821
- NVD CVE-2020-6821
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.