CVE-2021-43657: A Stored Cross-site scripting (XSS) vulnerability via MAster.php in Sourcecodetester Simple Client Management

Routine

MEDIUM 5.4DOWNGRADE

CVE-2021-43657 is a medium-severity flaw (CVSS 5.4) affecting simple client management system. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Stored Cross-site scripting (XSS) vulnerability via MAster.php in Sourcecodetester Simple Client Management System (SCMS) 1.0 allows remote attackers to inject arbitrary web script or HTML via the vulnerable input fields.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-79
Published	2022-12-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: simple client management system project

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

Am I affected?

Timeline

2022-12-22 02:15 UTCPublished CVE record published
2026-06-17 04:11 UTCUpdated Record last modified

simple client management system project simple client management system DOWNGRADE

Affected: 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

apt-cache policy simple-client-management-system || rpm -q simple-client-management-system || simple-client-management-system --version

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison simple-client-management-system sudo apt install simple-client-management-system=<VERSION_BEFORE_1.0> sudo apt-mark hold simple-client-management-system

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

dnf --showduplicates list simple-client-management-system sudo dnf downgrade simple-client-management-system-<VERSION_BEFORE_1.0> sudo dnf versionlock add simple-client-management-system

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-2021-43657?

simple client management system: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-43657 being exploited?

CVE-2021-43657 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-2021-43657 affect?

CVE-2021-43657 affects simple client management system. Severity is medium (CVSS 5.4). A Stored Cross-site scripting (XSS) vulnerability via MAster.php in Sourcecodetester Simple Client Management System (SCMS) 1.0 allows remote attackers to inject arbitrary web script or HTML via the vulnerable input fields.

How urgent is CVE-2021-43657?

Priority 33/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities

Related CVEs

CVE-2022-29984 CRITICAL 9.8 DOWNGRADE Simple Client Management System 1.0 is vulnerable to SQL Injection via /cms/admin/?page=client/view_client&id=
CVE-2022-29983 CRITICAL 9.8 DOWNGRADE Simple Client Management System 1.0 is vulnerable to SQL Injection via /cms/admin/?page=invoice/view_invoice&i
CVE-2022-29982 CRITICAL 9.8 DOWNGRADE Simple Client Management System 1.0 is vulnerable to SQL Injection via /cms/admin/maintenance/manage_service.p
CVE-2022-29981 CRITICAL 9.8 DOWNGRADE Simple Client Management System 1.0 is vulnerable to SQL Injection via /cms/classes/Users.php?f=delete.
CVE-2022-29980 CRITICAL 9.8 DOWNGRADE Simple Client Management System 1.0 is vulnerable to SQL Injection via /cms/admin/?page=user/manage_user&id=.

References

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