CVE-2016-10040 in Qt
Summary
by MITRE
Stack-based buffer overflow in QXmlSimpleReader in Qt 4.8.5 allows remote attackers to cause a denial of service (application crash) via a xml file with multiple nested open tags.
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2016-10040 represents a critical stack-based buffer overflow within the QXmlSimpleReader component of Qt version 4.8.5. This flaw resides in the XML parsing functionality that applications using Qt frameworks rely upon for processing structured data. The vulnerability specifically manifests when the parser encounters malformed XML content containing multiple nested open tags, creating a condition where the stack memory allocated for parsing operations exceeds its intended boundaries. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which classifies stack-based buffer overflow conditions that occur when insufficient bounds checking allows memory writes beyond allocated stack space. The flaw demonstrates characteristics consistent with CWE-787, which describes out-of-bounds writes that occur when a buffer is accessed beyond its allocated bounds, potentially leading to memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it creates potential pathways for more sophisticated attacks within environments where Qt-based applications process untrusted XML input. Remote attackers can exploit this weakness by crafting malicious XML files containing excessive nesting levels that trigger the buffer overflow during parsing operations. When the application attempts to parse such malformed input, the stack overflow causes the application to crash and terminate unexpectedly, resulting in a denial of service condition that can disrupt legitimate user access to the affected system. This vulnerability affects a wide range of applications that utilize Qt 4.8.5 for XML processing, including web applications, desktop software, and server-side components that accept XML data from external sources. The exploitation requires minimal privileges and can be executed remotely, making it particularly dangerous in networked environments where XML data flows between systems.
The technical exploitation of this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the Tactic of Execution, specifically targeting application execution through malformed input processing. Attackers can leverage this weakness to perform service disruption attacks, potentially using it as a stepping stone for more complex exploitation chains. The vulnerability demonstrates a clear path from initial exploitation to system availability impact, making it a preferred target for attackers seeking to disrupt services. Security practitioners should note that this vulnerability affects Qt 4.8.5 specifically, indicating that organizations using older versions of Qt frameworks may be at risk while newer versions have typically addressed this class of buffer overflow issues through improved input validation and memory management practices. The presence of such vulnerabilities in widely-used frameworks like Qt underscores the importance of regular security updates and patch management programs.
Mitigation strategies for CVE-2016-10040 primarily involve immediate patching of affected Qt installations to versions that contain fixed implementations of the XML parser. Organizations should prioritize updating their Qt framework components to versions that have addressed this buffer overflow vulnerability, typically found in Qt 4.8.6 and subsequent releases. Additionally, implementing input validation measures that sanitize XML content before processing can provide defense-in-depth protection against exploitation attempts. Network-level controls such as XML firewalls or content filtering systems can help detect and block malformed XML traffic that might exploit this vulnerability. Application developers should also consider implementing proper error handling and memory management practices within their Qt-based applications to minimize the impact of potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining current security patches for all software components, particularly those handling external input data, as even minor updates can address significant security gaps that could be exploited by threat actors.