| CVSS Meta Temp Score | Current Exploit Price (≈) | CTI Interest Score |
|---|---|---|
| 5.2 | $0-$5k | 0.00 |
Summary
A vulnerability has been found in Mozilla Firefox and Thunderbird and classified as problematic. Affected is an unknown function of the component Fullscreen Handler. The manipulation leads to ui layer. This vulnerability is documented as CVE-2020-26953. The attack can be initiated remotely. There is not any exploit available. The affected component should be upgraded.
Details
A vulnerability, which was classified as critical, has been found in Mozilla Firefox and Thunderbird (Web Browser) (the affected version unknown). This issue affects an unknown part of the component Fullscreen Handler. The manipulation with an unknown input leads to a ui layer vulnerability. Using CWE to declare the problem leads to CWE-1021. The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with. Impacted is confidentiality, integrity, and availability.
The weakness was released 12/09/2020 as mfsa2020-50. It is possible to read the advisory at mozilla.org. The identification of this vulnerability is CVE-2020-26953. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/09/2026).
Upgrading eliminates this vulnerability. The upgrade is hosted for download at mozilla.org.
The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-0337). Be aware that VulDB is the high quality source for vulnerability data.
Affected
- Open Source CentOS
- Debian Linux
- Red Hat Enterprise Linux
- Ubuntu Linux
- SUSE Linux
- Oracle Linux
- Gentoo Linux
- Open Source Arch Linux
- Mozilla Firefox
- Mozilla Firefox ESR
- Mozilla Thunderbird
Product
Type
Vendor
Name
License
Website
- Vendor: https://www.mozilla.org/
- Product: https://www.mozilla.org/en-US/firefox/
CPE 2.3
CPE 2.2
CVSSv4
VulDB Vector: 🔍VulDB Reliability: 🔍
CVSSv3
VulDB Meta Base Score: 5.3VulDB Meta Temp Score: 5.2
VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍
NVD Base Score: 4.3
NVD Vector: 🔍
CVSSv2
| AV | AC | Au | C | I | A |
|---|---|---|---|---|---|
| 💳 | 💳 | 💳 | 💳 | 💳 | 💳 |
| 💳 | 💳 | 💳 | 💳 | 💳 | 💳 |
| 💳 | 💳 | 💳 | 💳 | 💳 | 💳 |
| Vector | Complexity | Authentication | Confidentiality | Integrity | Availability |
|---|---|---|---|---|---|
| Unlock | Unlock | Unlock | Unlock | Unlock | Unlock |
| Unlock | Unlock | Unlock | Unlock | Unlock | Unlock |
| Unlock | Unlock | Unlock | Unlock | Unlock | Unlock |
VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍
NVD Base Score: 🔍
Exploiting
Class: Ui layerCWE: CWE-1021
CAPEC: 🔍
ATT&CK: 🔍
Physical: No
Local: No
Remote: Yes
Availability: 🔍
Status: Not defined
EPSS Score: 🔍
EPSS Percentile: 🔍
Price Prediction: 🔍
Current Price Estimation: 🔍
| 0-Day | Unlock | Unlock | Unlock | Unlock |
|---|---|---|---|---|
| Today | Unlock | Unlock | Unlock | Unlock |
Threat Intelligence
Interest: 🔍Active Actors: 🔍
Active APT Groups: 🔍
Countermeasures
Recommended: UpgradeStatus: 🔍
0-Day Time: 🔍
Upgrade: mozilla.org
Timeline
10/12/2020 🔍12/09/2020 🔍
12/09/2020 🔍
02/09/2026 🔍
Sources
Vendor: mozilla.orgProduct: mozilla.org
Advisory: mfsa2020-50
Status: Confirmed
Confirmation: 🔍
CVE: CVE-2020-26953 (🔍)
GCVE (CVE): GCVE-0-2020-26953
GCVE (VulDB): GCVE-100-165791
CERT Bund: WID-SEC-2026-0337 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen
Entry
Created: 12/09/2020 10:38Updated: 02/09/2026 10:28
Changes: 12/09/2020 10:38 (41), 12/14/2020 07:55 (6), 12/14/2020 08:02 (18), 02/09/2026 10:28 (22)
Complete: 🔍
Cache ID: 216::103
Be aware that VulDB is the high quality source for vulnerability data.
No comments yet. Languages: en.
Please log in to comment.