CVE-2020-26239: Scratch Addons is a WebExtension that supports both Chrome and Firefox

Q: How do I fix CVE-2020-26239?

scratch addons: upgrade to 1.3.2. Exact commands for each OS are on this page.

Q: Is CVE-2020-26239 being exploited?

CVE-2020-26239 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-26239 affect?

CVE-2020-26239 affects scratch addons. Severity is high (CVSS 7.6). 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

This month

HIGH 7.6UPGRADE

CVE-2020-26239 is a high-severity flaw (CVSS 7.6) affecting scratch addons. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 Li

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	1.0% (top 36%)
CISA exploited list	No
Weakness	CWE-79
Published	2020-11-23
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: scratchaddons

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-11-23 19:15 UTCPublished CVE record published
2026-06-17 03:07 UTCUpdated Record last modified

scratchaddons scratch addons UPGRADE

Affected: < 1.3.2

Fixed in: 1.3.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy scratch-addons || rpm -q scratch-addons || scratch-addons --version

2. UPGRADE to 1.3.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade scratch-addons

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade scratch-addons

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-26239?

scratch addons: upgrade to 1.3.2. Exact commands for each OS are on this page.

Is CVE-2020-26239 being exploited?

CVE-2020-26239 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-26239 affect?

CVE-2020-26239 affects scratch addons. Severity is high (CVSS 7.6). 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

How urgent is CVE-2020-26239?

Priority 43/100. High severity

Software pages

Google Chrome vulnerabilities · Mozilla Firefox vulnerabilities

References

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