CVE-2021-45380: AppCMS 2.0.101 has a XSS injection vulnerability in \templates\m\inc_head.php

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MEDIUM 6.1DOWNGRADE

CVE-2021-45380 is a medium-severity flaw (CVSS 6.1) affecting appcms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

AppCMS 2.0.101 has a XSS injection vulnerability in \templates\m\inc_head.php

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-01-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: appcms

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

Am I affected?

Timeline

2022-01-23 17:15 UTCPublished CVE record published
2026-06-17 04:13 UTCUpdated Record last modified

appcms appcms DOWNGRADE

Affected: 2.0.101

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.101

1. Check installed version

apt-cache policy appcms || rpm -q appcms || appcms --version

2. No fixed release: DOWNGRADE to a release before 2.0.101 (Debian / Ubuntu)

apt-cache madison appcms sudo apt install appcms=<VERSION_BEFORE_2.0.101> sudo apt-mark hold appcms

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

dnf --showduplicates list appcms sudo dnf downgrade appcms-<VERSION_BEFORE_2.0.101> sudo dnf versionlock add appcms

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Nuclei scan template: AppCMS - Cross-Site Scripting

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-2021-45380?

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

Is CVE-2021-45380 being exploited?

CVE-2021-45380 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-2021-45380 affect?

CVE-2021-45380 affects appcms. Severity is medium (CVSS 6.1). AppCMS 2.0.101 has a XSS injection vulnerability in \templates\m\inc_head.php

How urgent is CVE-2021-45380?

Priority 48/100. Public exploit reference

Software pages

PHP vulnerabilities

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References

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