How severe is CVE-2020-4061?

CVE-2020-4061 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-4061?

CVE-2020-4061 affects the following packages: october/backend (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2020-4061?

Update october/backend to 1.0.467 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-4061 is resolved across your whole dependency graph.

How do I detect CVE-2020-4061 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2020-4061 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2020-4061 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2020-4061, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2020-4061?

CVE-2020-4061 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 57th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2020-4061?

CVE-2020-4061 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2020-4061 published, and has it been updated?

CVE-2020-4061 was published on July 2, 2020 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2020-4061 — backend

MEDIUMFix: octobercms/october@b384954

CVE-2020-4061 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in october/backend. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for october/backend — see the affected versions and patch details below.

Cross-site Scripting in October

Also known asGHSA-3pc2-fm7p-q2vg

Published

Jul 2, 2020

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs57th percentile — riskier than 57% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘october/backend

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Impact

Pasting content copied from malicious websites into the Froala richeditor could result in a successful self-XSS attack.

Patches

Issue has been patched in Build 467 (v1.0.467).

Workarounds

Apply https://github.com/octobercms/october/commit/b384954a29b89117e1c0d6035b3ede4f46df67c5 to your installation manually if unable to upgrade to Build 467.

References

https://research.securitum.com/the-curious-case-of-copy-paste/

For more information

If you have any questions or comments about this advisory:

Email us at [email protected]

Threat Assessment

Assessed as Low given that by the nature of the attack it can only impact users that do it to themselves by copying and pasting from malicious websites.

Acknowledgements

Thanks to Michał Bentkowski of Securitum for finding the original issue in Froala and @tomaszstrojny for reporting the issue to the October CMS team.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`october/backend`	≥ 1.0.319&&< 1.0.467	1.0.467`composer require october/backend:^1.0.467`

Affected Products

1 product · 1 configurations

Application

octoberoctobercms

≥ 1.0.319 && < 1.0.467

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

In October from version 1.0.319 and before version 1.0.467, pasting cont…

research.securitum.comNVDJul 2020

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/backend, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update october/backend to 1.0.467 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-4061 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Impact Pasting content copied from malicious websites into the Froala richeditor could result in a successful self-XSS attack. ### Patches Issue has been patched in Build 467 (v1.0.467). ### Workarounds Apply https://github.com/octobercms/october/commit/b384954a29b89117e1c0d6035b3ede4f46df67c5 to your installation manually if unable to upgrade to Build 467. ### References - https://research.securitum.com/the-curious-case-of-copy-paste/ ### For more information If you have any questions or comments about this advisory: * Email us at [[email protected]](mailto:[email protected]) #