CVE-2011-1952 in Post Revolution
Summary
by MITRE
common.php in Post Revolution before 0.8.0c-2 allows remote attackers to cause a denial of service (infinite loop) via malformed HTML markup, as demonstrated by an a< sequence.
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Analysis
by VulDB Data Team • 01/16/2018
The vulnerability identified as CVE-2011-1952 affects the Post Revolution content management system version 0.8.0c-2 and earlier, presenting a significant security risk through a denial of service condition. This flaw specifically targets the common.php file, which serves as a core component in the system's processing pipeline. The vulnerability manifests when the application encounters malformed HTML markup containing sequences such as the a< pattern, which triggers an infinite loop condition in the processing logic. This type of vulnerability represents a classic example of improper input validation and insufficient error handling in web applications.
The technical implementation of this vulnerability stems from inadequate sanitization of HTML content within the Post Revolution framework. When the system processes HTML markup containing malformed sequences like a<, the parsing routine enters an infinite loop where it continuously processes the same malformed input without proper termination conditions. This behavior directly corresponds to CWE-835, which describes the weakness of infinite loops or infinite recursion in software applications. The flaw demonstrates poor defensive programming practices where the system fails to implement proper boundary checks and input validation mechanisms that would detect and terminate malformed processing sequences.
The operational impact of this vulnerability extends beyond simple service disruption, as it represents a potential vector for distributed denial of service attacks when exploited at scale. An attacker could craft malicious HTML content containing the problematic a< sequence and submit it through various application interfaces, potentially causing system resource exhaustion and application unavailability. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. The infinite loop condition consumes CPU cycles continuously, potentially leading to system instability and making the application unavailable to legitimate users, particularly in environments where the system handles user-generated content.
Mitigation strategies for this vulnerability require immediate implementation of input sanitization and validation mechanisms within the Post Revolution system. The most effective approach involves implementing comprehensive HTML sanitization routines that properly parse and normalize malformed markup before processing. System administrators should upgrade to Post Revolution version 0.8.0c-2 or later, which contains the necessary patches to address this specific vulnerability. Additionally, implementing rate limiting and input length restrictions on HTML content processing can provide additional defense in depth. Network-level protections such as web application firewalls can also help detect and block malicious HTML sequences before they reach the vulnerable processing logic, while monitoring systems should be configured to alert on unusual CPU utilization patterns that may indicate exploitation attempts.