Is Simple Custom CSS and JS safe to use?

Laskyr does not give safety verdicts. No known unpatched vulnerabilities in the latest version (3.54.3). As of 2026-11-01. 1 issue is on record for older versions; version 3.4 or newer fixes all of them that state a fix. Keep Simple Custom CSS and JS on the latest version (3.54.3) and remove it if you do not use it.

What is the latest version of Simple Custom CSS and JS?

3.54.3, according to wordpress.org (last updated 2026-10-08). It has 600,000+ active installs.

What should I do if my Simple Custom CSS and JS is out of date?

Take a backup, then update it from Dashboard > Updates (or run wp plugin update custom-css-js). If you cannot update right away, deactivate it until you can. If you think the site was already attacked, run a free scan at https://laskyr.com/scan.

Plugins · custom-css-js · data as of 2026-11-01

Is Simple Custom CSS and JS safe? Known vulnerabilities and latest version

Q: Which versions of Simple Custom CSS and JS are vulnerable?

Known issues on record (newest first): Cross-site scripting (XSS) (1.0 only, 1.1 only, 1.2 only, 1.3 only, 1.4 only, 1.5 only, 1.6 only, 2.0 only, 2.1 only, 2.2 only, 2.3 only, 2.4 only, 2.5 only, 2.6 only, 2.7 only, 2.8 only, 2.9 only, 2.10 only, 3.0 only, 3.1 only, 3.2 only, 3.3 only, fixed in 3.4). The full list with sources is on this page.

Latest version: 3.54.3
Last updated: 2026-10-08
Active installs: 600,000+
Known issues on record: 1
Unpatched in latest: 0
Tested up to WP: 7.1.4 · PHP 5.2.4+

Easily add Custom CSS or JS to your website with an awesome editor. — by SilkyPress

What to do

Update to the latest version (3.54.3). Anything older than 3.4 has at least one known issue listed below. Dashboard → Updates, or Plugins → “update now”.
If you cannot update right away, deactivate it until you can.
Turn on auto-updates for it: Plugins → “Enable auto-updates” on its row.
If you ran a vulnerable version and something looks off (spam pages, strange admins, redirects), run the free scan.

With WP-CLI: wp plugin get custom-css-js --field=version shows what you run; wp plugin update custom-css-js updates it.

Check your version

Known vulnerabilities

1 on record, newest first. “Affected” is the version range the source gives; “fixed in” is the version the source names, or (marked *) the first wordpress.org release after the last affected version.

medium 6.1 CVE-2017-2285 · published 2017-08-02

Cross-site scripting (XSS) in Simple Custom CSS and JS (1.0 only, 1.1 only, 1.2 only, 1.3 only, 1.4 only, 1.5 only, 1.6 only, 2.0 only, 2.1 only, 2.2 only, 2.3 only, 2.4 only, 2.5 only, 2.6 only, 2.7 only, 2.8 only, 2.9 only, 2.10 only, 3.0 only, 3.1 only, 3.2 only, 3.3 only)

Affected: 1.0 only, 1.1 only, 1.2 only, 1.3 only, 1.4 only, 1.5 only, 1.6 only, 2.0 only, 2.1 only, 2.2 only, 2.3 only, 2.4 only, 2.5 only, 2.6 only, 2.7 only, 2.8 only, 2.9 only, 2.10 only, 3.0 only, 3.1 only, 3.2 only, 3.3 only
Fixed in: 3.4 *
Access needed (per CVSS): No login needed; someone on the site has to click a link or open a page
Range from: NVD analysis · score by CISA ADP

Details from the advisory

Cross-site scripting vulnerability in Simple Custom CSS and JS prior to version 3.4 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.

NVD CVE-2017-2285 Code change (fix)wordpress.org jvn.jp wpvulndb.com

Recent activity

2026-10-08 — latest release on wordpress.org (3.54.3).
2017-08-02 — Cross-site scripting (XSS) disclosed (CVE-2017-2285), fixed in 3.4.

Free. We check the CVE feeds every day and email you only when a new issue for Simple Custom CSS and JS (custom-css-js) is published or a fix ships. Unsubscribe in one click.

Where this data comes from

Version, last update, installs: wordpress.org/plugins/custom-css-js (Plugins API), fetched 2026-11-01.
Vulnerabilities: NIST National Vulnerability Database (NVD), checked 2026-11-01. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Each record links to its CVE page and to the original advisory (Wordfence, Patchstack or WPScan) where there is one. We only list a CVE here when its references or its advisory name this exact plugin, so a few real issues may be missing; none should be about a different plugin. Spot an error? Email Daniel.

Badge for your site or docs (states facts with a date, not a verdict):

<a href="https://laskyr.com/plugins/custom-css-js"><img src="https://laskyr.com/plugins/custom-css-js/badge.svg" alt="Simple Custom CSS and JS vulnerability status"></a>

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