CVE-2020-12421: canonical ubuntu_linux Improper Certificate Validation
Vulnerability summary
CVE-2020-12421 is a medium (CVSS 6.5) Improper Certificate Validation vulnerability in canonical ubuntu_linux. EPSS estimates a 1.84% chance of exploitation in the next 30 days, higher than 78.7% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 27 · Related 13Timeline
- 09-07-2020PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user. This vulnerability affects Firefox ESR < 68.10, Firefox < 78, and Thunderbird < 68.10.0.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
EPSS trend
Probability
1.84%
Chance of exploitation in the next 30 days
Percentile
79%
Versus all other CVEs
30-day change
0.00 pp
From 1.84% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu5 products
- firefox< 78.0.1+build1-0ubuntu0.16.04.1 | < 78.0.1+build1-0ubuntu0.18.04.1 | < 78.0.1+build1-0ubuntu0.20.04.1
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
- thunderbird< 1:68.10.0+build1-0ubuntu0.16.04.1 | < 1:68.10.0+build1-0ubuntu0.18.04.1 | < 1:68.10.0+build1-0ubuntu0.20.04.1
Mozilla3 products
- firefox≥ unspecified, < 78 | < 78.0
- firefox_esr≥ unspecified, < 68.10 | < 68.10.0
- thunderbird≥ unspecified, < 68.10.0 | < 68.10.0
Debian2 products
- firefox-esr< 68.10.0esr-1
- thunderbird< 1:68.10.0-1
Canonical1 product
- ubuntu_linuxEOL16.04 | 18.04 | 19.10 | 20.04
4 vendors · 11 products
References
18 links- lists.opensuse.org/opensuse-security-announce/2020-07/msg00023.htmlVendor AdvisoryX Refsource SUSEBroken Link
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00026.htmlVendor AdvisoryX Refsource SUSEBroken Link
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.htmlVendor AdvisoryX Refsource SUSEBroken Link
- lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.htmlVendor AdvisoryX Refsource SUSEBroken Link
