CVE-2021-42077: PHP Event Calendar before 2021-09-03 allows SQL injection, as demonstrated by the /server/ajax/user_manager.ph

Q: How do I fix CVE-2021-42077?

php event calendar: upgrade to 2021-09-03. Exact commands for each OS are on this page.

Q: Is CVE-2021-42077 being exploited?

CVE-2021-42077 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-42077 affect?

CVE-2021-42077 affects php event calendar. Severity is critical (CVSS 9.8). PHP Event Calendar before 2021-09-03 allows SQL injection, as demonstrated by the /server/ajax/user_manager.php username parameter. This can be used to execute SQL statements directly on the database, allowing an adversary in some cases to

Q: How urgent is CVE-2021-42077?

Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-42077 is a critical-severity flaw (CVSS 9.8) affecting php event calendar. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PHP Event Calendar before 2021-09-03 allows SQL injection, as demonstrated by the /server/ajax/user_manager.php username parameter. This can be used to execute SQL statements directly on the database, allowing an adversary in some cases to completely compromise the database system. It can also be used to bypass the login form.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-89
Published	2021-11-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: kaysongroup

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

Am I affected?

Timeline

2021-11-08 04:15 UTCPublished CVE record published
2026-06-17 04:09 UTCUpdated Record last modified

kaysongroup php event calendar UPGRADE

Affected: < 2021-09-03

Fixed in: 2021-09-03

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy php-event-calendar || rpm -q php-event-calendar || php-event-calendar --version

2. UPGRADE to 2021-09-03 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade php-event-calendar

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade php-event-calendar

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2021-42077?

php event calendar: upgrade to 2021-09-03. Exact commands for each OS are on this page.

Is CVE-2021-42077 being exploited?

CVE-2021-42077 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-2021-42077 affect?

CVE-2021-42077 affects php event calendar. Severity is critical (CVSS 9.8). PHP Event Calendar before 2021-09-03 allows SQL injection, as demonstrated by the /server/ajax/user_manager.php username parameter. This can be used to execute SQL statements directly on the database, allowing an adversary in some cases to

How urgent is CVE-2021-42077?

Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2021-42078 MEDIUM 6.1 DOWNGRADE PHP Event Calendar through 2021-11-04 allows persistent cross-site scripting (XSS), as demonstrated by the /se

References

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