CVE-2021-34644: The Multiplayer Games WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SER

Q: How do I fix CVE-2021-34644?

multiplayer-plugin: upgrade to newer than 3.7. Exact commands for each OS are on this page.

Q: Is CVE-2021-34644 being exploited?

CVE-2021-34644 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-34644 affect?

CVE-2021-34644 affects multiplayer-plugin. Severity is medium (CVSS 6.1). The Multiplayer Games WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/multiplayergames.php file which allows attackers to inject arbitrary web scripts, in versions up to and i

Q: How urgent is CVE-2021-34644?

Priority 42/100. Public exploit reference

This month

MEDIUM 6.1UPGRADE

CVE-2021-34644 is a medium-severity flaw (CVSS 6.1) affecting multiplayer-plugin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Multiplayer Games WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/multiplayergames.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 3.7.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 39%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-08-16
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: multiplayer-plugin project

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

Am I affected?

Timeline

2021-08-16 19:15 UTCPublished CVE record published
2026-06-17 03:56 UTCUpdated Record last modified

multiplayer-plugin project multiplayer-plugin UPGRADE

Affected: <= 3.7

Fixed in: newer than 3.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy multiplayer-plugin || rpm -q multiplayer-plugin || multiplayer-plugin --version

2. UPGRADE to newer than 3.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade multiplayer-plugin

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade multiplayer-plugin

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-34644?

multiplayer-plugin: upgrade to newer than 3.7. Exact commands for each OS are on this page.

Is CVE-2021-34644 being exploited?

CVE-2021-34644 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-2021-34644 affect?

CVE-2021-34644 affects multiplayer-plugin. Severity is medium (CVSS 6.1). The Multiplayer Games WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/multiplayergames.php file which allows attackers to inject arbitrary web scripts, in versions up to and i

How urgent is CVE-2021-34644?

Priority 42/100. Public exploit reference

Software pages

WordPress vulnerabilities · PHP vulnerabilities

References

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