CVE-2021-43509: SQL Injection vulnerability exists in Sourcecodester Simple Client Management System 1.0 via the id parameter

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2021-43509 is a critical-severity flaw (CVSS 9.8) affecting simple client management system. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

SQL Injection vulnerability exists in Sourcecodester Simple Client Management System 1.0 via the id parameter in view-service.php.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-89
Published	2022-02-01
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

2022-02-01 14:15 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-2021-43509?

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

Is CVE-2021-43509 being exploited?

CVE-2021-43509 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-2021-43509 affect?

CVE-2021-43509 affects simple client management system. Severity is critical (CVSS 9.8). SQL Injection vulnerability exists in Sourcecodester Simple Client Management System 1.0 via the id parameter in view-service.php.

How urgent is CVE-2021-43509?

Priority 64/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

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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