Cross-site scripting in Mozilla Firefox
Priority LOW 30CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Partial Red Hat: 16 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-79.
Summary
Firefox sometimes ran the onload handler for SVG elements that the DOM sanitizer decided to remove, resulting in JavaScript being executed after pasting attacker-controlled data into a contenteditable element. This vulnerability affects Firefox < 81, Thunderbird < 78.3, and Firefox ESR < 78.3.
Why it matters now
EPSS 0.01594 75th percentileScored 2026-11-07
Fix Partial Firefox (Mozilla): 81Thunderbird (Mozilla): 78.3+1 more productRed Hat: 10 advisoriesRed Hat: 16 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 | before 81 | 81 | Patch available | CNA |
| Mozilla | Thunderbird | before 78.3 | 78.3 | Patch available | CNA |
| Mozilla | Firefox ESR | before 78.3 | 78.3 | Patch available | CNA |
- Firefox VendorMozilla Affected before 81 Fixed in 81 Patch available CNA
- Thunderbird VendorMozilla Affected before 78.3 Fixed in 78.3 Patch available CNA
- Firefox ESR VendorMozilla Affected before 78.3 Fixed in 78.3 Patch available CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 81.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 78.3 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 78.3 | 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 81.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.3 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.3 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 (Mozilla) Fixed in 81
- Fix · CNA Thunderbird (Mozilla) Fixed in 78.3
- Fix · CNA Firefox ESR (Mozilla) Fixed in 78.3
Red Hat 10 advisories
- RHSA-2020:4163 Released 2020-10-01 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Client (v. 7) thunderbird-78.3.1-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-78.3.1-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) thunderbird-78.3.1-1.el7_9
- RHSA-2020:4158 Released 2020-10-01 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Desktop (v. 6) thunderbird-78.3.1-1.el6_10
- Red Hat Enterprise Linux Server Optional (v. 6) thunderbird-78.3.1-1.el6_10
- Red Hat Enterprise Linux Workstation (v. 6) thunderbird-78.3.1-1.el6_10
- RHSA-2020:4155 Released 2020-10-01 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 8) thunderbird-78.3.1-1.el8_2
Show 7 more Red Hat advisories
- RHSA-2020:4157 Released 2020-10-01 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) thunderbird-78.3.1-1.el8_1
- RHSA-2020:4156 Released 2020-10-01 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.0) thunderbird-78.3.1-1.el8_0
- RHSA-2020:4080 Released 2020-09-30 · Red Hat rating Importantfirefox security and bug fix update
- Red Hat Enterprise Linux Client (v. 7) firefox-78.3.0-1.el7_9
- Red Hat Enterprise Linux Client Optional (v. 7) firefox-78.3.0-1.el7_9
- Red Hat Enterprise Linux Server (v. 7) firefox-78.3.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) firefox-78.3.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) firefox-78.3.0-1.el7_9
- Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-78.3.0-1.el7_9
- RHSA-2020:3835 Released 2020-09-24 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Desktop (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux Desktop Optional (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux HPC Node Optional (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux Server (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux Server Optional (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux Workstation (v. 6) firefox-78.3.0-1.el6_10
- Red Hat Enterprise Linux Workstation Optional (v. 6) firefox-78.3.0-1.el6_10
- RHSA-2020:3832 Released 2020-09-24 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 8) firefox-78.3.0-1.el8_2
- RHSA-2020:3833 Released 2020-09-24 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v. 8.1) firefox-78.3.0-1.el8_1
- RHSA-2020:3834 Released 2020-09-24 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream E4S (v. 8.0) firefox-78.3.0-1.el8_0
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 — openSUSE-SU-2020:1780
4 records Highest priority Priority MEDIUM 2 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2020-12352 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12347 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12351 Open redirect in Mozilla FirefoxPriority LOW 31
- Advisory ·
Mozilla Firefox, Firefox ESR, Thunderbird — openSUSE-SU-2020:1785
4 records Highest priority Priority MEDIUM 2 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2020-12352 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12347 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12351 Open redirect in Mozilla FirefoxPriority LOW 31
Show 2 more groups
- Advisory ·
Mozilla Firefox, Firefox ESR, Thunderbird — GLSA-202010-02
4 records Highest priority Priority MEDIUM 2 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2020-12352 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12347 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12351 Open redirect in Mozilla FirefoxPriority LOW 31
- Advisory ·
Mozilla Firefox, Firefox ESR, Thunderbird — DSA-4770
4 records Highest priority Priority MEDIUM 2 MEDIUM, 2 LOW
Other records, highest priority first
- TI-2020-12352 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12347 Use after free in Mozilla FirefoxPriority MEDIUM 42
- TI-2020-12351 Open redirect in Mozilla FirefoxPriority LOW 31
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 AppStream (v. 8) | Fixed | RHSA-2020:3832, RHSA-2020:4155 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.0) | Fixed | RHSA-2020:3834, RHSA-2020:4156 |
| Red Hat Enterprise Linux AppStream EUS (v. 8.1) | Fixed | RHSA-2020:3833, RHSA-2020:4157 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2020:4080, RHSA-2020:4163 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2020:4080 |
| Red Hat Enterprise Linux Desktop (v. 6) | Fixed | RHSA-2020:3835, RHSA-2020:4158 |
| Red Hat Enterprise Linux Desktop Optional (v. 6) | Fixed | RHSA-2020:3835 |
| Red Hat Enterprise Linux HPC Node Optional (v. 6) | Fixed | RHSA-2020:3835 |
| Red Hat Enterprise Linux Server (v. 6) | Fixed | RHSA-2020:3835 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2020:4080 |
| Red Hat Enterprise Linux Server Optional (v. 6) | Fixed | RHSA-2020:3835, RHSA-2020:4158 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2020:4080, RHSA-2020:4163 |
| Red Hat Enterprise Linux Workstation (v. 6) | Fixed | RHSA-2020:3835, RHSA-2020:4158 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2020:4080, RHSA-2020:4163 |
| Red Hat Enterprise Linux Workstation Optional (v. 6) | Fixed | RHSA-2020:3835 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2020:4080 |
Timeline
- 2026-10-02 Threatist record created from CVE-2020-15676
- 2026-10-03 Alias added: GHSA-m5jf-7x3g-f295
References
Advisory 9
- https://www.mozilla.org/security/advisories/mfsa2020-43/
- https://www.mozilla.org/security/advisories/mfsa2020-44/
- https://www.mozilla.org/security/advisories/mfsa2020-42/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1646140
- DSA-4770
- [debian-lts-announce] 20201016 [SECURITY] [DLA 2408-1] thunderbird security update
- GLSA-202010-02
- 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-2020-15676 · CVE Program
- CVE-2020-15676 · NVD
- FIRST EPSS
- GHSA-m5jf-7x3g-f295 · GitHub Advisory Database · CC BY 4.0
- CVE-2020-15676 · 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