How severe is CVE-2018-10366?

CVE-2018-10366 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2018-10366?

CVE-2018-10366 affects the following packages: rainlab/user-plugin (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2018-10366?

Update rainlab/user-plugin to 1.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-10366 is resolved across your whole dependency graph.

How do I detect CVE-2018-10366 in my Packagist dependencies?

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

How do I mitigate CVE-2018-10366 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-2018-10366 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2018-10366, including 1 documented proof-of-concept exploit on Exploit-DB and 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-2018-10366?

CVE-2018-10366 has an EPSS (Exploit Prediction Scoring System) score of 2.4%, placing it in the 84th 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-2018-10366?

CVE-2018-10366 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-2018-10366 published, and has it been updated?

CVE-2018-10366 was published on April 25, 2018 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-2018-10366 — user-plugin

MEDIUMFix: rainlab/user-plugin@098c2bc

CVE-2018-10366 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in rainlab/user-plugin. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for rainlab/user-plugin — see the affected versions and patch details below.

User Plugin for October CSS Allows XSS

Also known asGHSA-x5jc-34xf-c24q

Published

Apr 25, 2018

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

2 known

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs84th percentile — riskier than 84% 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

🐘rainlab/user-plugin

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

An issue was discovered in the Users (aka Front-end user management) plugin 1.4.5 for October CMS. XSS exists in the name field.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`rainlab/user-plugin`	all versions	1.5.0`composer require rainlab/user-plugin:^1.5.0`

Affected Products

1 product · 1 configurations

Application

useruser_project

1 version

1.4.5

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.

EDB-44546webappsphp

October CMS User Plugin 1.4.5 - Persistent Cross-Site Scripting

by 0xB9 · Apr 26, 2018

Exploit-DB Source

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rainlab/user-plugin, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rainlab/user-plugin to 1.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-10366 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

An issue was discovered in the Users (aka Front-end user management) plugin 1.4.5 for October CMS. XSS exists in the name field.

O3 Security · Impact-Aware SCA

Is CVE-2018-10366 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template or Metasploit module yet. 2 public proof-of-concept references are listed on this page.

Timeline

Disclosed

Apr 25, 2018

First exploit

Apr 26, 2018

1 day after disclosure — rapid exploitation

Last updated

Oct 20, 2026

Identifiers

CVE-2018-10366

GHSA-x5jc-34xf-c24q

References

Advisorynvd.nist.gov · CVE 2018 10366 Fixgithub.com · 098c2bc907443d67e9e18645f850e3de42941d20 Webexploit-db.com Packagegithub.com · user plugin Evidenceexploit-db.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs with CWE-79 are rated as high or higher (top: critical).

CVE-2026-55649CVE-2026-113787CVE-2026-44267CVE-2026-96632CVE-2026-9086CVE-2026-118246CVE-2026-118251CVE-2026-118253Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026