CVE-2021-40910: There is a reflective cross-site scripting (XSS) vulnerability in the PHPCMS V9.6.3 management side.

Routine

MEDIUM 6.1DOWNGRADE

CVE-2021-40910 is a medium-severity flaw (CVSS 6.1) affecting phpcms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

There is a reflective cross-site scripting (XSS) vulnerability in the PHPCMS V9.6.3 management side.

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	0.7% (top 49%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-06-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: phpcms

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

Am I affected?

Timeline

2022-06-15 16:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

phpcms phpcms DOWNGRADE

Affected: 9.6.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.6.3

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 9.6.3 (Debian / Ubuntu)

apt-cache madison phpcms sudo apt install phpcms=<VERSION_BEFORE_9.6.3> sudo apt-mark hold phpcms

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

dnf --showduplicates list phpcms sudo dnf downgrade phpcms-<VERSION_BEFORE_9.6.3> sudo dnf versionlock add phpcms

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-2021-40910?

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

Is CVE-2021-40910 being exploited?

CVE-2021-40910 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-2021-40910 affect?

CVE-2021-40910 affects phpcms. Severity is medium (CVSS 6.1). There is a reflective cross-site scripting (XSS) vulnerability in the PHPCMS V9.6.3 management side.

How urgent is CVE-2021-40910?

Priority 39/100. Public exploit reference

Related CVEs

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CVE-2020-22200 MEDIUM 5.3 DOWNGRADE Directory Traversal vulnerability in phpCMS 9.1.13 via the q parameter to public_get_suggest_keyword.

References

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