CVE-2023-48831 in Availability Booking Calendar
Summary
by MITRE • 12/07/2023
A lack of rate limiting in pjActionAJaxSend in Availability Booking Calendar 5.0 allows attackers to cause resource exhaustion.
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Analysis
by VulDB Data Team • 03/02/2026
The vulnerability identified as CVE-2023-48831 represents a critical security flaw in the Availability Booking Calendar plugin version 5.0, specifically within the pjActionAJaxSend function. This issue stems from insufficient rate limiting mechanisms that permit unauthorized users to exploit the system's resource allocation capabilities through repeated requests. The vulnerability manifests when attackers submit multiple rapid requests to the ajax endpoint, potentially overwhelming the server's processing capabilities and leading to denial of service conditions. The absence of proper request throttling allows malicious actors to consume excessive computational resources, memory, and processing power, ultimately degrading system performance or causing complete service interruption.
The technical implementation of this vulnerability resides in the plugin's handling of asynchronous ajax requests through the pjActionAJaxSend function, which lacks adequate controls to monitor or restrict the frequency of incoming requests. This flaw aligns with CWE-770, which addresses the allocation of resources without proper limits or controls, and represents a classic example of resource exhaustion attacks. The vulnerability can be exploited through automated tools or scripts that rapidly submit booking requests or other ajax-based operations, making it particularly dangerous in environments where the plugin handles high volumes of legitimate user traffic. Attackers can leverage this weakness to perform sustained resource exhaustion attacks that may not be immediately apparent to system administrators, as the malicious activity can be disguised as normal user behavior.
The operational impact of CVE-2023-48831 extends beyond simple denial of service scenarios, as it can compromise the availability of critical booking services and potentially provide attackers with opportunities to conduct further reconnaissance or exploit additional system weaknesses. When attackers successfully exhaust system resources, legitimate users may experience degraded performance, failed booking requests, or complete inability to access the calendar functionality. The vulnerability can also serve as a stepping stone for more sophisticated attacks, as compromised systems often provide attackers with additional attack surface or information that can be leveraged for privilege escalation. Organizations relying on the Availability Booking Calendar plugin may face significant business disruption, particularly in high-traffic environments where booking systems are critical for revenue generation or service delivery.
Mitigation strategies for this vulnerability should include implementing robust rate limiting mechanisms at multiple levels, including application-level controls within the plugin itself, web application firewalls, and server-level restrictions. The recommended approach involves configuring time-based request limits, implementing request counting mechanisms, and establishing connection throttling policies that prevent any single client from overwhelming the system. Security measures should also include monitoring and logging of ajax request patterns to identify anomalous behavior that may indicate exploitation attempts. Organizations should consider implementing CAPTCHA mechanisms for high-risk operations and establishing automated alerting systems that notify administrators of unusual traffic patterns. Additionally, regular security updates and patches should be applied promptly to address known vulnerabilities, with the implementation of security best practices such as input validation, output encoding, and proper error handling to reduce the overall attack surface. The solution aligns with ATT&CK technique T1499.004, which focuses on resource exhaustion attacks, and requires comprehensive defensive measures that address both the immediate vulnerability and broader system security posture.