CVE-2024-42191 in Traveler for Microsoft Outlook
Summary
by MITRE • 05/30/2025
HCL Traveler for Microsoft Outlook (HTMO) is susceptible to a COM hijacking vulnerability which could allow an attacker to modify or replace the application with malicious content.
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Analysis
by VulDB Data Team • 10/31/2025
The vulnerability identified as CVE-2024-42191 affects HCL Traveler for Microsoft Outlook, a widely used email synchronization and collaboration tool that enables users to access their email, calendar, and contacts from various devices. This COM hijacking vulnerability represents a critical security flaw that exploits the Windows Component Object Model architecture to gain unauthorized access to the system. The vulnerability stems from improper handling of COM registration and object instantiation within the HTMO application, creating opportunities for malicious actors to intercept or manipulate the application's execution flow.
The technical flaw manifests through the insecure registration of COM components within the Windows registry, where HTMO fails to properly validate or authenticate the legitimacy of COM objects that are loaded during application startup. This weakness allows attackers to register malicious COM components with the same CLSID values as legitimate ones, effectively hijacking the application's execution path. The vulnerability specifically impacts the way the application resolves and loads COM objects, creating a window of opportunity where malicious code can be executed with the privileges of the user running the application. This type of vulnerability falls under CWE-755, which addresses improper handling of exceptions or errors in component object model interactions, and aligns with ATT&CK technique T1550.001 for hijacking execution flow through component object model.
The operational impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation could enable attackers to execute arbitrary code, steal sensitive information, or establish persistence mechanisms within the targeted environment. Since HTMO is commonly deployed in enterprise environments where users often have elevated privileges, the potential for lateral movement and further compromise increases significantly. The vulnerability affects not only individual user systems but also organizational infrastructure, as compromised endpoints can serve as launching points for broader network attacks. Attackers could leverage this vulnerability to deploy additional malware, conduct credential harvesting, or establish backdoor access that persists across system reboots.
Mitigation strategies should focus on immediate registry hardening and component validation measures to prevent unauthorized COM object registration. Organizations should implement strict access controls on the Windows registry entries related to HTMO and enforce application whitelisting policies to restrict execution of unauthorized COM components. The recommended approach includes disabling unnecessary COM registration entries, implementing proper code signing validation, and regularly auditing COM object registrations within the system. Additionally, network segmentation and monitoring solutions should be deployed to detect anomalous COM activity that might indicate exploitation attempts. Security teams should also consider implementing the principle of least privilege for HTMO installations and ensure that users have appropriate permissions to modify system components. Regular security updates from HCL should be prioritized, while organizations may need to implement temporary workarounds such as disabling specific COM functionality until proper patches are deployed. The vulnerability underscores the importance of maintaining secure application deployment practices and continuous monitoring of system integrity to prevent unauthorized modifications to critical components.