Observable discrepancy in Mozilla Thunderbird
Priority LOW 21CWE-203Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- High
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 1 fixed, 2 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-203.
Summary
NSS has shown timing differences when performing DSA signatures, which was exploitable and could eventually leak private keys. This vulnerability affects Thunderbird < 68.9.0, Firefox < 77, and Firefox ESR < 68.9.
Why it matters now
EPSS 0.00651 51st percentileScored 2026-11-07
Fix Partial Thunderbird (Mozilla): 68.9.0Firefox (Mozilla): 77+1 more productRed Hat: 1 advisoryRed Hat: 1 fixed, 2 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mozilla | Thunderbird | before 68.9.0 | 68.9.0 | Patch available | CNA |
| Mozilla | Firefox | before 77 | 77 | Patch available | CNA |
| Mozilla | Firefox ESR | before 68.9 | 68.9 | Patch available | CNA |
- Thunderbird VendorMozilla Affected before 68.9.0 Fixed in 68.9.0 Patch available CNA
- Firefox VendorMozilla Affected before 77 Fixed in 77 Patch available CNA
- Firefox ESR VendorMozilla Affected before 68.9 Fixed in 68.9 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 77.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 68.9.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 68.9.0 | Vulnerable | Mozilla |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
- cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 77.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 68.9.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 68.9.0 Vulnerable ·Mozilla
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
Remediation
- Fix · CNA Thunderbird (Mozilla) Fixed in 68.9.0
- Fix · CNA Firefox (Mozilla) Fixed in 77
- Fix · CNA Firefox ESR (Mozilla) Fixed in 68.9
Red Hat 1 advisory
- RHSA-2020:3280 Released 2020-08-03 · Red Hat rating Moderatenss and nspr security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 8) nspr-4.25.0-2.el8_2, nspr-devel-4.25.0-2.el8_2, nss-3.53.1-11.el8_2 +9
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Mozilla Firefox, Firefox ESR, Thunderbird — USN-4421-1
10 records Highest priority Priority MEDIUM 5 MEDIUM, 5 LOW
Other records, highest priority first
- TI-2020-09937 Use after free in Mozilla Firefox ESRPriority MEDIUM 43
- TI-2020-09935 Reachable assertion in Mozilla Firefox ESRPriority MEDIUM 43
- TI-2020-09938 Race condition in Mozilla Firefox ESRPriority MEDIUM 42
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2020:3280 |
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2020-12399
- 2026-10-03 Alias added: GHSA-fq62-4j88-qq7x
- 2026-10-14 EPSS moved to the 50th–90th percentile
References
Advisory 8
- https://www.mozilla.org/security/advisories/mfsa2020-20/
- https://www.mozilla.org/security/advisories/mfsa2020-21/
- https://www.mozilla.org/security/advisories/mfsa2020-22/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1631576
- DSA-4726
- USN-4421-1
- GLSA-202007-49
- [debian-lts-announce] 20200929 [SECURITY] [DLA 2388-1] nss security update
More Mozilla Firefox vulnerabilities
- TI-2024-08981 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.8
- TI-2022-09832 Use after free in Mozilla Firefox KEVCVSS 3.1CRITICAL 9.6
- TI-2019-08769 Improper input validation in Mozilla Firefox ESR KEVCVSS 3.1CRITICAL 10.0
- TI-2010-03577 Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before… KEVCVSS 3.1CRITICAL 9.8
- TI-2023-04799 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
- TI-2023-04477 Out-of-bounds write in Google Chrome KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2020-12399 · CVE Program
- CVE-2020-12399 · NVD
- FIRST EPSS
- GHSA-fq62-4j88-qq7x · GitHub Advisory Database · CC BY 4.0
- CVE-2020-12399 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences