Use after free in Mozilla Firefox ESR
Priority MEDIUM 47CWE-416Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 17 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
Mozilla developers and community members reported memory safety bugs present in Firefox 81 and Firefox ESR 78.3. 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 ESR < 78.4, Firefox < 82, and Thunderbird < 78.4.
Why it matters now
EPSS 0.02674 85th percentileScored 2026-11-07
Fix Partial Firefox ESR (Mozilla): 78.4Firefox (Mozilla): 82+1 more productRed Hat: 11 advisoriesRed Hat: 17 fixed, 1 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 | Firefox ESR | before 78.4 | 78.4 | Patch available | CNA |
| Mozilla | Firefox | before 82 | 82 | Patch available | CNA |
| Mozilla | Thunderbird | before 78.4 | 78.4 | Patch available | CNA |
- Firefox ESR VendorMozilla Affected before 78.4 Fixed in 78.4 Patch available CNA
- Firefox VendorMozilla Affected before 82 Fixed in 82 Patch available CNA
- Thunderbird VendorMozilla Affected before 78.4 Fixed in 78.4 Patch available CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 82.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 78.4 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 78.4 | Vulnerable | Mozilla |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:* | 15.1 | Vulnerable | openSUSE |
| cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:* | 15.2 | Vulnerable | openSUSE |
- cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 82.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.4 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.4 Vulnerable ·Mozilla
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:* Versions 15.1 Vulnerable ·openSUSE
- cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:* Versions 15.2 Vulnerable ·openSUSE
Remediation
- Fix · CNA Firefox ESR (Mozilla) Fixed in 78.4
- Fix · CNA Firefox (Mozilla) Fixed in 82
- Fix · CNA Thunderbird (Mozilla) Fixed in 78.4
Red Hat 11 advisories
- RHSA-2020:4947 Released 2020-11-05 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Desktop (v. 6) thunderbird-78.4.0-1.el6_10
- Red Hat Enterprise Linux Server Optional (v. 6) thunderbird-78.4.0-1.el6_10
- Red Hat Enterprise Linux Workstation (v. 6) thunderbird-78.4.0-1.el6_10
- RHSA-2020:4945 Released 2020-11-05 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.4.0-1.el8_1
- RHSA-2020:4944 Released 2020-11-05 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird-78.4.0-1.el8_0
Show 8 more Red Hat advisories
- RHSA-2020:4948 Released 2020-11-05 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.2) thunderbird-78.4.0-1.el8_2
- RHSA-2020:4909 Released 2020-11-04 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Client (v. 7) thunderbird-78.4.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.4.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.4.0-1.el7_9
- RHSA-2020:4913 Released 2020-11-04 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.4.0-1.el8_3
- RHSA-2020:4330 Released 2020-10-26 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Desktop (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux Desktop Optional (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux Server (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux Server Optional (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux Workstation (v. 6) firefox-78.4.0-2.el6_10
- Red Hat Enterprise Linux Workstation Optional (v. 6) firefox-78.4.0-2.el6_10
- RHSA-2020:4317 Released 2020-10-22 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 8) firefox-78.4.0-1.el8_2
- RHSA-2020:4315 Released 2020-10-22 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.4.0-1.el8_1
- RHSA-2020:4310 Released 2020-10-22 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Client (v. 7) firefox-78.4.0-1.el7_9
- Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.4.0-1.el7_9
- Red Hat Enterprise Linux Server (v. 7) firefox-78.4.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.4.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) firefox-78.4.0-1.el7_9
- Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.4.0-1.el7_9
- RHSA-2020:4311 Released 2020-10-22 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox-78.4.0-1.el8_0
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Mozilla Firefox 82
5 records Highest priority Priority MEDIUM 2 MEDIUM, 3 LOW
Other records, highest priority first
- TI-2020-12358 Use after free in Mozilla FirefoxPriority MEDIUM 45
- TI-2020-12355 When multiple WASM threads had a reference to a module, and were looking up exported…Priority LOW 35
- TI-2020-12356 Origin validation error in Mozilla FirefoxPriority LOW 29
Vendor assessments
Red Hat
Red Hat rating: Important. 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 AppStream (v. 8) | Fixed | RHSA-2020:4317, RHSA-2020:4913 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.0) | Fixed | RHSA-2020:4311, RHSA-2020:4944 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.1) | Fixed | RHSA-2020:4315, RHSA-2020:4945 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.2) | Fixed | RHSA-2020:4948 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2020:4310, RHSA-2020:4909 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2020:4310 |
| Red Hat Enterprise Linux Desktop (v. 6) | Fixed | RHSA-2020:4330, RHSA-2020:4947 |
| Red Hat Enterprise Linux Desktop Optional (v. 6) | Fixed | RHSA-2020:4330 |
| Red Hat Enterprise Linux HPC Node Optional (v. 6) | Fixed | RHSA-2020:4330 |
| Red Hat Enterprise Linux Server (v. 6) | Fixed | RHSA-2020:4330 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2020:4310 |
| Red Hat Enterprise Linux Server Optional (v. 6) | Fixed | RHSA-2020:4330, RHSA-2020:4947 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2020:4310, RHSA-2020:4909 |
| Red Hat Enterprise Linux Workstation (v. 6) | Fixed | RHSA-2020:4330, RHSA-2020:4947 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2020:4310, RHSA-2020:4909 |
| Red Hat Enterprise Linux Workstation Optional (v. 6) | Fixed | RHSA-2020:4330 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2020:4310 |
Timeline
- 2026-10-02 Threatist record created from CVE-2020-15683
- 2026-10-03 Alias added: GHSA-q4v9-gx3p-c65m
References
Advisory 11
- https://www.mozilla.org/security/advisories/mfsa2020-45/
- https://www.mozilla.org/security/advisories/mfsa2020-47/
- https://www.mozilla.org/security/advisories/mfsa2020-46/
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1576843%2C1656987%2C1660954%2C1662760%2C1663439%2C1666140
- openSUSE-SU-2020:1732
- DSA-4780
- openSUSE-SU-2020:1748
- [debian-lts-announce] 20201027 [SECURITY] [DLA 2416-1] thunderbird security update
- GLSA-202010-08
- openSUSE-SU-2020:1780
- openSUSE-SU-2020:1785
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-2020-15683 · CVE Program
- CVE-2020-15683 · NVD
- FIRST EPSS
- GHSA-q4v9-gx3p-c65m · GitHub Advisory Database · CC BY 4.0
- CVE-2020-15683 · Red Hat security data · CC BY 4.0
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