How severe is CVE-2020-26239?

CVE-2020-26239 has a CVSS 3.x base score of 7.6, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity high, and availability none.

Is CVE-2020-26239 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26239?

CVE-2020-26239 affects Scratchaddons Scratch Addons. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26239?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-26239 published?

CVE-2020-26239 was published on 2020-11-23 and last updated on 2026-06-17.

CVE-2020-26239

CVE-2020-26239 is a high-severity vulnerability in Scratchaddons Scratch Addons with a CVSS 3.x base score of 7.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 7.6)
CVSS v2: 3.5
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Scratchaddons Scratch Addons
Published: 2020-11-23
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-26239?: 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.
How severe is CVE-2020-26239?: CVE-2020-26239 has a CVSS 3.x base score of 7.6, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity high, and availability none.
Is CVE-2020-26239 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26239?: CVE-2020-26239 affects Scratchaddons Scratch Addons. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26239?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-26239 published?: CVE-2020-26239 was published on 2020-11-23 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:scratchaddons:scratch_addons:*:*:*:*:*:*:*:*

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