CVE-2018-16636: Nucleus CMS 3.70 allows HTML Injection via the index.php body parameter.

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MEDIUM 6.5DOWNGRADE

CVE-2018-16636 is a medium-severity flaw (CVSS 6.5) affecting nucleus cms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Nucleus CMS 3.70 allows HTML Injection via the index.php body parameter.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-79
Published	2018-12-10
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: nucleuscms

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-12-10 19:29 UTCPublished CVE record published
2026-06-17 01:44 UTCUpdated Record last modified

nucleuscms nucleus cms DOWNGRADE

Affected: 3.70

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.70

1. Check installed version

apt-cache policy nucleus-cms || rpm -q nucleus-cms || nucleus-cms --version

2. No fixed release: DOWNGRADE to a release before 3.70 (Debian / Ubuntu)

apt-cache madison nucleus-cms sudo apt install nucleus-cms=<VERSION_BEFORE_3.70> sudo apt-mark hold nucleus-cms

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nucleus-cms sudo dnf downgrade nucleus-cms-<VERSION_BEFORE_3.70> sudo dnf versionlock add nucleus-cms

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-16636?

nucleus cms: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-16636 being exploited?

CVE-2018-16636 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-16636 affect?

CVE-2018-16636 affects nucleus cms. Severity is medium (CVSS 6.5). Nucleus CMS 3.70 allows HTML Injection via the index.php body parameter.

How urgent is CVE-2018-16636?

Priority 44/100. Public exploit reference

Software pages

PHP vulnerabilities

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CVE-2011-3760 MEDIUM 5.0 DOWNGRADE Nucleus 3.61 allows remote attackers to obtain sensitive information via a direct request to a .php file, whic
CVE-2009-0929 MEDIUM 5.0 UPGRADE Directory traversal vulnerability in the media manager in Nucleus CMS before 3.40 allows remote attackers to r

References

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