CVE-2020-26239
Cross-Site Scripting in Scratch browser addons
Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. If the victim visited a specific website, the More Links addon of the Scratch Addons extension used incorrect regular expression which caused the HTML-escaped values to be unescaped, leading to XSS. Scratch Addons version 1.3.2 fixes the bug. The extension will be automatically updated by the browser. More Links addon can be disabled via the option of the extension.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Cross-Site Scripting in Scratch browser addons
Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. If the victim visited a specific website, the More Links addon of the Scratch Addons extension used incorrect regular expression which caused the HTML-escaped values to be unescaped, leading to XSS. Scratch Addons version 1.3.2 fixes the bug. The extension will be automatically updated by the browser. More Links addon can be disabled via the option of the extension.
- Record
CVE-2020-26239- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2020-18845
Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. If the victim visited a specific website, the More Links addon of the Scratch Addons extension used incorrect regular expression which caused the HTML-escaped values to be unescaped, leading to XSS. Scratch Addons version 1.3.2 fixes the bug. The extension will be automatically updated by the browser. More Links addon can be disabled via the option of the extension.
- Record
EUVD-2020-18845- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:N - Updated
- 2026-11-03
NVD
Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. If the victim visited a specific website, the More Links addon of the Scratch Addons extension used incorrect regular expression which caused the HTML-escaped values to be unescaped, leading to XSS. Scratch Addons version 1.3.2 fixes the bug. The extension will be automatically updated by the browser. More Links addon can be disabled via the option of the extension.
- Record
CVE-2020-26239- CVSS 3.1
- 7.6 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:N - CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 3.5 Low
AV:N/AC:M/Au:S/C:N/I:P/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. If the victim visited a specific website, the More Links addon of the Scratch Addons extension used incorrect regular expression which caused the HTML-escaped values to be unescaped, leading to XSS. Scratch Addons version 1.3.2 fixes the bug. The extension will be automatically updated by the browser. More Links addon can be disabled via the option of the extension.
- Record
CVE-2020-26239- CVSS 3.1
- 5.4 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-26239 is a high vulnerability (CVSS 7.6) in Scratchaddons Scratch Addons, published November 23, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.03%, the 64th percentile. No source names a fixed version.
References
github.com/ScratchAddons/ScratchAddons/security/advisories/GHSA-6qfq-px3r-xj4p