CVE-2021-47917: Simple CMS 2.1 contains a persistent cross-site scripting vulnerability in user input parameters that allows r

Routine

MEDIUM 6.4DOWNGRADE

CVE-2021-47917 is a medium-severity flaw (CVSS 6.4) affecting simple cms php. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Simple CMS 2.1 contains a persistent cross-site scripting vulnerability in user input parameters that allows remote attackers to inject malicious script code. Attackers can exploit the newUser and editUser modules to inject persistent scripts that execute on user list preview, potentially leading to session hijacking and application manipulation.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-02-01
Last modified	2026-06-17

Publisher (CNA): VulnCheck · Vendor: simplephpscripts

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

Am I affected?

Timeline

2026-02-01 13:15 UTCPublished CVE record published
2026-06-17 04:18 UTCUpdated Record last modified

simplephpscripts simple cms php DOWNGRADE

Affected: 2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.1

1. Check installed version

apt-cache policy simple-cms-php || rpm -q simple-cms-php || simple-cms-php --version

2. No fixed release: DOWNGRADE to a release before 2.1 (Debian / Ubuntu)

apt-cache madison simple-cms-php sudo apt install simple-cms-php=<VERSION_BEFORE_2.1> sudo apt-mark hold simple-cms-php

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

dnf --showduplicates list simple-cms-php sudo dnf downgrade simple-cms-php-<VERSION_BEFORE_2.1> sudo dnf versionlock add simple-cms-php

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-2021-47917?

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

Is CVE-2021-47917 being exploited?

CVE-2021-47917 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-2021-47917 affect?

CVE-2021-47917 affects simple cms php. Severity is medium (CVSS 6.4). Simple CMS 2.1 contains a persistent cross-site scripting vulnerability in user input parameters that allows remote attackers to inject malicious script code. Attackers can exploit the newUser and editUser modules to inject persistent scrip

How urgent is CVE-2021-47917?

Priority 34/100. Public exploit reference

Software pages

PHP vulnerabilities

Related CVEs

CVE-2021-47919 MEDIUM 6.4 DOWNGRADE Simple CMS 2.1 contains a non-persistent cross-site scripting vulnerability in the preview.php file's id param
CVE-2021-47918 HIGH 8.1 DOWNGRADE Simple CMS 2.1 contains a remote SQL injection vulnerability that allows privileged attackers to inject unfilt

References

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