CVE-2021-47736: CMSimple_XH 1.7.4 contains an authenticated remote code execution vulnerability in the content editing functio

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HIGH 7.2DOWNGRADE

CVE-2021-47736 is a high-severity flaw (CVSS 7.2) affecting cmsimple xh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

CMSimple_XH 1.7.4 contains an authenticated remote code execution vulnerability in the content editing functionality that allows administrative users to upload malicious PHP files. Attackers with valid credentials can exploit the CSRF token mechanism to create a PHP shell file that enables arbitrary command execution on the server.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	7.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	1.1% (top 35%)
CISA exploited list	No
Weakness	CWE-94
Published	2025-12-23
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: cmsimple-xh

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

Am I affected?

Timeline

2025-12-23 20:15 UTCPublished CVE record published
2026-06-17 04:18 UTCUpdated Record last modified

cmsimple-xh cmsimple xh DOWNGRADE

Affected: 1.7.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.7.4

1. Check installed version

apt-cache policy cmsimple-xh || rpm -q cmsimple-xh || cmsimple-xh --version

2. No fixed release: DOWNGRADE to a release before 1.7.4 (Debian / Ubuntu)

apt-cache madison cmsimple-xh sudo apt install cmsimple-xh=<VERSION_BEFORE_1.7.4> sudo apt-mark hold cmsimple-xh

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

dnf --showduplicates list cmsimple-xh sudo dnf downgrade cmsimple-xh-<VERSION_BEFORE_1.7.4> sudo dnf versionlock add cmsimple-xh

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-2021-47736?

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

Is CVE-2021-47736 being exploited?

CVE-2021-47736 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-2021-47736 affect?

CVE-2021-47736 affects cmsimple xh. Severity is high (CVSS 7.2). CMSimple_XH 1.7.4 contains an authenticated remote code execution vulnerability in the content editing functionality that allows administrative users to upload malicious PHP files. Attackers with valid credentials can exploit the CSRF token

How urgent is CVE-2021-47736?

Priority 46/100. High severity; Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2025-63589 HIGH 7.1 DOWNGRADE A reflected XSS vulnerability exists in CMSimple_XH 1.8's index.php router when attacker-controlled path segme
CVE-2025-63588 HIGH 7.1 DOWNGRADE An unauthenticated reflected cross-site scripting vulnerability in the query handling of CMSimpleXH allows rem
CVE-2024-34452 MEDIUM 6.1 DOWNGRADE CMSimple_XH 1.7.6 allows XSS by uploading a crafted SVG document.

References

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