CVE-2011-4462 in Plone
Summary
by MITRE
Plone 4.1.3 and earlier computes hash values for form parameters without restricting the ability to trigger hash collisions predictably, which allows remote attackers to cause a denial of service (CPU consumption) by sending many crafted parameters.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 03/04/2025
The vulnerability identified as CVE-2011-4462 affects Plone content management systems version 4.1.3 and earlier, representing a significant security flaw that enables remote attackers to execute denial of service attacks through predictable hash collision exploitation. This vulnerability resides in the application's handling of form parameters and demonstrates a critical weakness in the system's input validation and hash function implementation. The flaw specifically targets the hash computation mechanism used by Plone when processing HTTP form data, creating an avenue for attackers to consume excessive CPU resources through carefully crafted parameter sequences. The vulnerability operates by exploiting the predictable nature of hash collisions in the underlying hash table implementation, allowing attackers to manipulate the system's computational resources in a way that can severely impact service availability.
The technical implementation of this vulnerability stems from the use of a hash table data structure that lacks proper collision resistance mechanisms when processing form parameters. When Plone receives HTTP requests containing form data, it computes hash values for each parameter to store and retrieve them efficiently within internal hash tables. However, the implementation does not adequately restrict the ability to generate predictable hash collisions, enabling attackers to craft specific parameter combinations that will cause hash table operations to degrade from optimal O(1) performance to O(n) worst-case scenarios. This degradation occurs because multiple parameters will map to the same hash bucket, creating a chain of linked elements that must be traversed sequentially during lookup operations. The vulnerability specifically affects the hash computation algorithm used by the application's parameter processing layer, which fails to implement collision-resistant hashing mechanisms that would prevent attackers from deliberately triggering hash table performance degradation.
The operational impact of CVE-2011-4462 extends beyond simple service disruption to encompass significant computational resource exhaustion that can render the affected Plone system completely unresponsive. Attackers can exploit this vulnerability by sending multiple HTTP requests containing specially crafted form parameters that will cause the system to spend excessive CPU cycles processing hash collisions. The resource consumption pattern typically results in sustained high CPU utilization that can lead to system instability, application timeouts, and complete service unavailability for legitimate users. This type of denial of service attack can be particularly devastating in production environments where Plone systems handle critical business operations and user interactions, as the attack can effectively shut down the entire content management platform. The vulnerability's impact is amplified by the fact that it requires minimal computational resources to execute, making it an attractive attack vector for adversaries seeking to disrupt services without requiring sophisticated attack infrastructure.
Mitigation strategies for CVE-2011-4462 should focus on both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities in future implementations. The primary recommendation involves upgrading to Plone versions 4.1.4 and later, which contain patches specifically designed to address the hash collision vulnerability by implementing more robust hash computation mechanisms and collision handling. Organizations should also consider implementing rate limiting and input validation measures at network boundaries to prevent excessive parameter processing, although these measures represent temporary workarounds rather than permanent solutions. From a security architecture perspective, this vulnerability highlights the importance of implementing collision-resistant hashing algorithms in applications that process untrusted input data, particularly when using hash-based data structures for performance optimization. The flaw aligns with CWE-327, which addresses weak cryptographic hash functions and improper hash implementation, and demonstrates how poor hash table design can create significant security implications. Additionally, this vulnerability intersects with ATT&CK technique T1499.004, which covers network denial of service attacks, by enabling attackers to consume system resources through predictable hash table operations that can be exploited remotely without requiring authentication or privileged access.