CVE-2023-48840: A lack of rate limiting in pjActionAjaxSend in Appointment Scheduler 3.0 allows attackers to cause resource ex

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2023-48840 is a high-severity flaw (CVSS 7.5) affecting appointment scheduler. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A lack of rate limiting in pjActionAjaxSend in Appointment Scheduler 3.0 allows attackers to cause resource exhaustion.

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	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 36%)
CISA exploited list	No
Weakness	CWE-400
Published	2023-12-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: phpjabbers

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

Am I affected?

Timeline

2023-12-07 07:15 UTCPublished CVE record published
2026-06-17 06:35 UTCUpdated Record last modified

phpjabbers appointment scheduler DOWNGRADE

Affected: 3.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.0

1. Check installed version

apt-cache policy appointment-scheduler || rpm -q appointment-scheduler || appointment-scheduler --version

2. No fixed release: DOWNGRADE to a release before 3.0 (Debian / Ubuntu)

apt-cache madison appointment-scheduler sudo apt install appointment-scheduler=<VERSION_BEFORE_3.0> sudo apt-mark hold appointment-scheduler

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

dnf --showduplicates list appointment-scheduler sudo dnf downgrade appointment-scheduler-<VERSION_BEFORE_3.0> sudo dnf versionlock add appointment-scheduler

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-2023-48840?

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

Is CVE-2023-48840 being exploited?

CVE-2023-48840 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-2023-48840 affect?

CVE-2023-48840 affects appointment scheduler. Severity is high (CVSS 7.5). A lack of rate limiting in pjActionAjaxSend in Appointment Scheduler 3.0 allows attackers to cause resource exhaustion.

How urgent is CVE-2023-48840?

Priority 52/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-48841 HIGH 8.8 DOWNGRADE Appointment Scheduler 3.0 is vulnerable to CSV Injection via a Language > Labels > Export action.
CVE-2023-48839 MEDIUM 5.4 DOWNGRADE Appointment Scheduler 3.0 is vulnerable to Multiple Stored Cross-Site Scripting (XSS) issues via the name, plu
CVE-2023-48838 MEDIUM 5.4 DOWNGRADE Appointment Scheduler 3.0 is vulnerable to Multiple HTML Injection issues via the SMS API Key or Default Count
CVE-2023-36127 HIGH 7.5 DOWNGRADE User enumeration is found in in PHPJabbers Appointment Scheduler 3.0
CVE-2023-36126 MEDIUM 6.1 DOWNGRADE There is a Cross Site Scripting (XSS) vulnerability in the "theme" parameter of preview.php in PHPJabbers Appo

References

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