CVE-2023-48840 in Appointment Scheduler
Summary
by MITRE • 12/07/2023
A lack of rate limiting in pjActionAjaxSend in Appointment Scheduler 3.0 allows attackers to cause resource exhaustion.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 03/02/2026
The vulnerability identified as CVE-2023-48840 resides within the Appointment Scheduler plugin version 3.0, specifically affecting the pjActionAjaxSend functionality. This issue represents a critical security flaw that enables malicious actors to exploit the absence of rate limiting mechanisms, potentially leading to resource exhaustion attacks against affected systems. The vulnerability manifests when the plugin fails to implement proper request throttling or rate limiting controls for its AJAX endpoints, creating an avenue for attackers to flood the system with excessive requests.
The technical flaw stems from the lack of implementation for rate limiting controls within the pjActionAjaxSend function, which processes AJAX requests for appointment scheduling operations. This absence allows attackers to submit numerous requests in rapid succession without any restrictions on the number or frequency of submissions. The vulnerability directly maps to CWE-770, which addresses the allocation of resources without proper limits or throttling mechanisms, and aligns with ATT&CK technique T1499.004 for resource exhaustion attacks. The flaw enables attackers to consume excessive system resources such as CPU cycles, memory allocation, and database connections through repeated AJAX calls that trigger the pjActionAjaxSend functionality.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can compromise the overall stability and performance of systems running the affected plugin. Attackers can leverage this weakness to exhaust server resources, potentially causing legitimate users to experience service disruption or complete system unavailability. The resource exhaustion can affect database performance, application response times, and overall system availability, making it particularly dangerous for production environments where appointment scheduling systems handle critical business operations. This vulnerability can be exploited through automated tools to amplify the attack impact, making it a significant concern for organizations relying on the Appointment Scheduler plugin for their scheduling needs.
Mitigation strategies for CVE-2023-48840 should focus on implementing proper rate limiting mechanisms within the plugin's AJAX handling functions. System administrators should consider applying immediate patches or updates from the plugin vendor once available, while implementing temporary workarounds such as server-level rate limiting using web application firewalls or reverse proxies. The implementation of request throttling controls that monitor and limit the frequency of AJAX requests to pjActionAjaxSend endpoints will help prevent abuse. Organizations should also implement monitoring solutions to detect unusual request patterns that may indicate exploitation attempts, and establish baseline performance metrics to quickly identify when resource exhaustion attacks are occurring. Additionally, network-level controls such as implementing API rate limiting and connection limiting can provide defense-in-depth measures against this specific vulnerability.