CVE-2021-36621: Sourcecodester Online Covid Vaccination Scheduler System 1.0 is vulnerable to SQL Injection

This week

HIGH 8.1REMOTEDOWNGRADE

CVE-2021-36621 is a high-severity flaw (CVSS 8.1) affecting online covid vaccination scheduler system. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Sourcecodester Online Covid Vaccination Scheduler System 1.0 is vulnerable to SQL Injection. The username parameter is vulnerable to time-based SQL injection. Upon successful dumping the admin password hash, an attacker can decrypt and obtain the plain-text password. Hence, the attacker could authenticate as Administrator.

Why this priority

High 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	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	2.1% (top 19%)
CISA exploited list	No
Weakness	CWE-89
Published	2021-07-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: online covid vaccination scheduler system project

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

Am I affected?

Timeline

2021-07-30 14:15 UTCPublished CVE record published
2026-06-17 03:58 UTCUpdated Record last modified

online covid vaccination scheduler system project online covid vaccination scheduler 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 online-covid-vaccination-scheduler-system || rpm -q online-covid-vaccination-scheduler-system || online-covid-vaccination-scheduler-system --version

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

apt-cache madison online-covid-vaccination-scheduler-system sudo apt install online-covid-vaccination-scheduler-system=<VERSION_BEFORE_1.0> sudo apt-mark hold online-covid-vaccination-scheduler-system

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

dnf --showduplicates list online-covid-vaccination-scheduler-system sudo dnf downgrade online-covid-vaccination-scheduler-system-<VERSION_BEFORE_1.0> sudo dnf versionlock add online-covid-vaccination-scheduler-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-2021-36621?

online covid vaccination scheduler system: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-36621 being exploited?

CVE-2021-36621 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-2021-36621 affect?

CVE-2021-36621 affects online covid vaccination scheduler system. Severity is high (CVSS 8.1). Sourcecodester Online Covid Vaccination Scheduler System 1.0 is vulnerable to SQL Injection. The username parameter is vulnerable to time-based SQL injection. Upon successful dumping the admin password hash, an attacker can decrypt and obta

How urgent is CVE-2021-36621?

Priority 59/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-41930 MEDIUM 6.1 DOWNGRADE Cross site scripting (XSS) vulnerability in Sourcecodester Online Covid Vaccination Scheduler System v1 by ore
CVE-2021-37803 HIGH 8.1 DOWNGRADE An SQL Injection vulnerability exists in Sourcecodester Online Covid Vaccination Scheduler System 1.0 via the
CVE-2021-36622 CRITICAL 9.8 DOWNGRADE Sourcecodester Online Covid Vaccination Scheduler System 1.0 is affected vulnerable to Arbitrary File Upload

References

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