CVE-2011-2975 in MapServer
Summary
by MITRE
Double free vulnerability in the msAddImageSymbol function in mapsymbol.c in MapServer before 6.0.1 might allow remote attackers to cause a denial of service (application crash) or have unspecified other impact via crafted mapfile data.
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Analysis
by VulDB Data Team • 03/07/2025
The CVE-2011-2975 vulnerability represents a critical double free error in MapServer's msAddImageSymbol function within the mapsymbol.c file, affecting versions prior to 6.0.1. This flaw resides in the handling of mapfile data processing where the application fails to properly manage memory allocation and deallocation sequences. The vulnerability manifests when crafted malicious mapfile data is processed by the affected software, creating a scenario where the same memory block gets freed twice during the symbol addition process. Such memory management errors typically occur when the application does not properly validate or track memory references, leading to undefined behavior that can be exploited by remote attackers. The vulnerability operates at the intersection of memory safety and application logic, specifically within the image symbol processing subsystem that handles map rendering operations.
The technical implementation of this double free vulnerability stems from improper memory management within the msAddImageSymbol function, which processes image symbol data for map rendering. When the application encounters crafted mapfile data, it attempts to allocate memory for image symbols and subsequently frees this memory without proper validation of the allocation state. This creates a condition where the same memory address may be passed to the free() function twice, causing memory corruption that leads to application instability. The flaw is particularly dangerous because it can be triggered through user-supplied mapfile content, making it a remote code execution or denial of service vector. This type of vulnerability falls under CWE-415, which specifically addresses double free conditions in memory management, and can be mapped to ATT&CK technique T1203 for process injection and T1499 for network denial of service attacks.
The operational impact of CVE-2011-2975 extends beyond simple application crashes to potentially enable more sophisticated attacks depending on the deployment environment. Remote attackers can leverage this vulnerability to cause denial of service conditions that render map rendering services unavailable, disrupting critical geographic information system operations. In environments where MapServer serves as a core component of web mapping applications, such as those used by government agencies, transportation networks, or emergency response systems, this vulnerability could lead to significant operational disruption. The unspecified other impacts mentioned in the original description suggest that under certain conditions, the memory corruption could potentially allow for arbitrary code execution or privilege escalation. Organizations using MapServer for web mapping services, particularly those exposed to untrusted user input, face substantial risk from this vulnerability. The impact is amplified in multi-tenant environments where a single compromised mapfile could affect multiple users or applications.
Mitigation strategies for CVE-2011-2975 require immediate patching of affected MapServer installations to version 6.0.1 or later, which contains the necessary memory management fixes. Organizations should implement input validation measures to sanitize all mapfile data before processing, including implementing strict parsing rules and content filtering mechanisms. Network segmentation and access controls can help limit exposure by restricting access to mapfile processing functions to trusted sources only. Additionally, implementing application-level firewalls or web application firewalls can help detect and block malicious mapfile content before it reaches the vulnerable code paths. Regular security assessments and vulnerability scanning should be conducted to identify other potential memory management issues within the application stack. The remediation approach should align with industry best practices for memory safety, including implementing proper memory allocation tracking, using memory debugging tools, and conducting thorough code reviews focused on resource management patterns. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts targeting this vulnerability, as the double free condition often produces detectable network traffic patterns or system behavior anomalies.