CVE-2012-5506 in Plone
Summary
by MITRE
python_scripts.py in Plone before 4.2.3 and 4.3 before beta 1 allows remote attackers to cause a denial of service (infinite loop) via an RSS feed request for a folder the user does not have permission to access.
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Analysis
by VulDB Data Team • 03/13/2019
The vulnerability identified as CVE-2012-5506 affects the Plone content management system and represents a significant denial of service weakness that can be exploited remotely by unauthorized users. This flaw exists in python_scripts.py, a critical component within Plone's architecture that handles various scripting operations. The vulnerability specifically manifests when processing RSS feed requests for folder resources that authenticated users lack proper permissions to access, creating a condition where the system enters an infinite loop state that consumes excessive computational resources and effectively renders the service unavailable to legitimate users.
The technical implementation of this vulnerability stems from inadequate input validation and permission checking mechanisms within the RSS feed processing module. When a malicious user submits an RSS feed request targeting a restricted folder, the system fails to properly handle the permission denial scenario, instead falling into a recursive or iterative processing loop that never terminates. This behavior aligns with CWE-835, which categorizes infinite loops as a common weakness in software systems where loop termination conditions are not properly enforced. The flaw demonstrates poor error handling practices where the application does not gracefully manage access control violations, leading to resource exhaustion rather than proper rejection of unauthorized requests.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by attackers to consume significant system resources including cpu cycles and memory allocation. This makes it particularly dangerous in production environments where Plone systems may be under heavy load or where resource constraints already exist. The infinite loop condition can cause the application server to become unresponsive, potentially leading to cascading failures in dependent services or systems that rely on Plone for content management. This type of attack falls under the ATT&CK technique T1499.004, which describes denial of service through resource exhaustion, and represents a classic example of how improper access control implementation can create exploitable conditions.
Organizations running affected versions of Plone should prioritize immediate patching to address this vulnerability, as the remediation process is straightforward and involves updating to versions 4.2.3 or later 4.3 beta releases where the issue has been resolved. The fix typically involves implementing proper permission validation checks and ensuring that access denied conditions are handled gracefully without entering recursive processing states. Additionally, system administrators should consider implementing rate limiting mechanisms and monitoring for unusual RSS feed request patterns that might indicate exploitation attempts. Network-level protections such as web application firewalls can also help detect and block malicious RSS feed requests targeting restricted resources, providing an additional layer of defense against this specific attack vector.