CVE-2021-30150: Composr 10.0.36 allows XSS in an XML script.

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MEDIUM 6.1DOWNGRADE

CVE-2021-30150 is a medium-severity flaw (CVSS 6.1) affecting composr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Composr 10.0.36 allows XSS in an XML script.

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	2.8% (top 14%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-04-06
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ocproducts

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

Am I affected?

Timeline

2021-04-06 06:15 UTCPublished CVE record published
2026-06-17 03:49 UTCUpdated Record last modified

ocproducts composr DOWNGRADE

Affected: 10.0.36

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0.36

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 10.0.36 (Debian / Ubuntu)

apt-cache madison composr sudo apt install composr=<VERSION_BEFORE_10.0.36> sudo apt-mark hold composr

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

dnf --showduplicates list composr sudo dnf downgrade composr-<VERSION_BEFORE_10.0.36> sudo dnf versionlock add composr

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.

Exploit-DB: Composr CMS 10.0.36 - 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-2021-30150?

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

Is CVE-2021-30150 being exploited?

CVE-2021-30150 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-2021-30150 affect?

CVE-2021-30150 affects composr. Severity is medium (CVSS 6.1). Composr 10.0.36 allows XSS in an XML script.

How urgent is CVE-2021-30150?

Priority 48/100. Public exploit reference

Related CVEs

CVE-2021-46360 HIGH 8.8 UPGRADE Authenticated remote code execution (RCE) in Composr-CMS 10.0.39 and earlier allows remote attackers to execut
CVE-2021-30149 CRITICAL 9.8 DOWNGRADE Composr 10.0.36 allows upload and execution of PHP files.

References

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