CVE-2020-26239

Name: CVE-2020-26239
Creator: NVD / NIST
Published: 2020-11-23T19:15:11.117+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 1.02%

Last modified Jun 17, 2026

CVE-2020-26239 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. Scratch Addons is a WebExtension that supports both Chrome and Firefox. Scratch Addons before version 1.3.2 is vulnerable to DOM-based XSS. EPSS estimates a 1.02% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

1.02%

58.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Scratchaddons	Scratch Addons	< 1.3.2

References

https://github.com/ScratchAddons/ScratchAddons/blob/a471893df403f86c9182970678175d4772a0690c/addons/more-links/userscript.js#L15Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/commit/b9a52d6532c8514254c7cc1d8e18710dbedc41ffPatch, Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/releases/tag/v1.3.2Release Notes, Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/security/advisories/GHSA-6qfq-px3r-xj4pPatch, Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/blob/a471893df403f86c9182970678175d4772a0690c/addons/more-links/userscript.js#L15Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/commit/b9a52d6532c8514254c7cc1d8e18710dbedc41ffPatch, Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/releases/tag/v1.3.2Release Notes, Third Party Advisory
https://github.com/ScratchAddons/ScratchAddons/security/advisories/GHSA-6qfq-px3r-xj4pPatch, Third Party Advisory

Timeline

Published: Nov 23, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-26239?

How severe is CVE-2020-26239?

CVE-2020-26239 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 1.02% probability of exploitation in the next 30 days.

How do I fix CVE-2020-26239?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-26239?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST