CVE-2026-104656 in Telerik Fiddler Everywhere
Summary
by MITRE • 11/06/2026
Improper neutralization of input in the sessions grid in Progress Telerik Fiddler Everywhere 8.3.0 and earlier allows an attacker to execute backend IPC commands by convincing a user to open a specially crafted SAZ file.
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Analysis
by VulDB Data Team • 11/06/2026
The vulnerability identified as Improper Neutralization of Input within the session management interface of Progress Telerik Fiddler Everywhere versions prior to 8.3.0 represents a significant security risk rooted in inadequate validation and sanitization mechanisms for input data processed by the application's grid component. This flaw specifically affects how the software handles serialized archive files, commonly known as SAZ files, which are used to store captured HTTP traffic sessions. When an attacker crafts a malicious SAZ file containing specially designed payloads within its metadata or session objects, they can exploit the lack of rigorous input validation in the rendering and processing logic of the sessions grid. The core technical failure lies in the application's assumption that data loaded from these files is inherently safe, leading to a situation where potentially dangerous strings are passed directly to backend processes without adequate sanitization checks for command injection patterns or unsafe object instantiation requests.
From an operational perspective, this vulnerability enables Remote Code Execution through Inter-Process Communication mechanisms rather than traditional network-based exploitation vectors. By convincing a victim user to open the malicious SAZ file within their Fiddler Everywhere instance, the attacker triggers the execution of arbitrary commands on the host system via IPC channels that are typically reserved for internal application communication but lack sufficient access controls or input filtering in this specific context. This attack vector relies heavily on social engineering tactics, as it requires user interaction to load the payload into memory and trigger the processing pipeline. Once executed, these backend IPC commands can operate with the same privileges as the currently logged-in user, potentially allowing for data exfiltration, system configuration changes, or further lateral movement within a compromised environment depending on the scope of permissions granted to the Fiddler application process.
This vulnerability aligns closely with CWE-20 Improper Input Validation and CWE-78 OS Command Injection, as it involves the failure to neutralize special elements that could be interpreted by an operating system or backend service during command execution. Furthermore, in terms of tactical classification under the MITRE ATT&CK framework, this scenario maps to T1564.002 Hidden Files and Directories for initial access via deceptive file types, followed by T1059 Command and Scripting Interpreter through the IPC mechanism used to execute the injected commands. The exploitation chain demonstrates how desktop applications that handle user-generated or third-party data files can become vectors for system compromise if they do not strictly enforce security boundaries between UI rendering components and backend execution engines.
To mitigate this risk, users must immediately upgrade to Progress Telerik Fiddler Everywhere version 8.3.0 or later, where the developers have implemented stricter input validation protocols within the sessions grid component. These updates likely include enhanced sanitization routines that detect and block malicious patterns in SAZ file contents before they are processed by backend services. Additionally, organizations should enforce strict application whitelisting policies to limit the privileges of Fiddler Everywhere processes, ensuring that even if an exploit is successful, its impact on the broader system is contained. Security awareness training regarding the risks of opening untrusted network capture files is also recommended to reduce the likelihood of users falling victim to social engineering attempts designed to deliver such malicious payloads.