Searching for a single word from the address bar caused an mDNS request to be sent on the…
Priority LOW 32Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
Searching for a single word from the address bar caused an mDNS request to be sent on the local network searching for a hostname consisting of that string; resulting in an information leak. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
Why it matters now
EPSS 0.01354 71st percentileScored 2026-11-07
Fix Fixed Firefox (Mozilla): 83Firefox ESR (Mozilla): 78.5+1 more product
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 83 | 83 | Patch available | CNA |
| Mozilla | Firefox ESR | before 78.5 | 78.5 | Patch available | CNA |
| Mozilla | Thunderbird | before 78.5 | 78.5 | Patch available | CNA |
- Firefox VendorMozilla Affected before 83 Fixed in 83 Patch available CNA
- Firefox ESR VendorMozilla Affected before 78.5 Fixed in 78.5 Patch available CNA
- Thunderbird VendorMozilla Affected before 78.5 Fixed in 78.5 Patch available CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* | before 83.0 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 78.5 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 78.5 | Vulnerable | Mozilla |
| cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Microsoft |
- cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* Versions before 83.0 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 78.5 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 78.5 Vulnerable ·Mozilla
- cpe:2.3:o:microsoft:windows:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Microsoft
Remediation
- Fix · CNA Firefox (Mozilla) Fixed in 83
- Fix · CNA Firefox ESR (Mozilla) Fixed in 78.5
- Fix · CNA Thunderbird (Mozilla) Fixed in 78.5
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
Not affected: 4 products
- Red Hat Enterprise Linux 5
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2020-26966
- 2026-10-03 Alias added: GHSA-c627-2gcf-x56f
References
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-2020-26966 · CVE Program
- CVE-2020-26966 · NVD
- FIRST EPSS
- GHSA-c627-2gcf-x56f · GitHub Advisory Database · CC BY 4.0
- CVE-2020-26966 · 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