How severe is CVE-2018-16637?

CVE-2018-16637 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-2018-16637?

CVE-2018-16637 affects the following packages: evolutioncms/evolution (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2018-16637?

Update evolutioncms/evolution to 1.4.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-16637 is resolved across your whole dependency graph.

How do I detect CVE-2018-16637 in my Packagist dependencies?

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

How do I mitigate CVE-2018-16637 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-2018-16637 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2018-16637, 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-2018-16637?

CVE-2018-16637 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 47th 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-2018-16637?

CVE-2018-16637 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-2018-16637 published, and has it been updated?

CVE-2018-16637 was published on December 28, 2018 and was last updated on October 24, 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-2018-16637 — evolution

MEDIUMFix: evolution-cms/evolution@2b8aaa6

CVE-2018-16637 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in evolutioncms/evolution. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for evolutioncms/evolution — see the affected versions and patch details below.

Evolution CMS Stored Cross-site Scripting (XSS)

Also known asGHSA-8h24-3cjr-xxmh

Published

Dec 28, 2018

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs47th percentile — riskier than 47% 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

🐘evolutioncms/evolution

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

Evolution CMS 1.4.x prior to 1.4.6 allows XSS via the page weblink title parameter to the manager/ URI.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`evolutioncms/evolution`	≥ 1.4&&< 1.4.6	1.4.6`composer require evolutioncms/evolution:^1.4.6`

Affected Products

1 product · 1 configurations

Application

evolution cmsmodx

≥ 1.4.0 && ≤ 1.4.7

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.

Evolution CMS 1.4.x allows XSS via the page weblink title parameter to t…

github.comNVDFeb 2019

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for evolutioncms/evolution, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update evolutioncms/evolution to 1.4.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-16637 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

Evolution CMS 1.4.x prior to 1.4.6 allows XSS via the page weblink title parameter to the manager/ URI.

O3 Security · Impact-Aware SCA

Is CVE-2018-16637 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.4/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.0/AV:N/AC:L/PR:L/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. 1 public proof-of-concept reference is listed on this page.

Timeline

Disclosed

Dec 28, 2018

First exploit

Feb 26, 2019

Last updated

Oct 24, 2026

Identifiers

CVE-2018-16637

GHSA-8h24-3cjr-xxmh

References

Advisorynvd.nist.gov · CVE 2018 16637 Webgithub.com Webgithub.com · 2b8aaa6224997155de0fe9440ad106bd98dc4f4b Packagegithub.com · evolution Evidencegithub.com · evolution xss stored.pdf

Related vulnerabilities

Also affects evolutioncms/evolution

This CVE is medium severity, in line with the other 3 CVEs affecting evolutioncms/evolution.

CVE-2023-43340CVE-2023-43341CVE-2018-16638

Same weakness: CWE-79

This CVE is medium severity; 5 of 5 other CVEs with CWE-79 are rated as high or higher (top: critical).

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

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026