CVE-2026-25952 in FreeRDP
Summary
by MITRE • 02/25/2026
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, `xf_SetWindowMinMaxInfo` dereferences a freed `xfAppWindow` pointer because `xf_rail_get_window` in `xf_rail_server_min_max_info` returns an unprotected pointer from the `railWindows` hash table, and the main thread can concurrently delete the window (via a window delete order) while the RAIL channel thread is still using the pointer. Version 3.23.0 fixes the issue.
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Analysis
by VulDB Data Team • 05/13/2026
The vulnerability CVE-2026-25952 represents a critical use-after-free condition in FreeRDP's implementation of the Remote Desktop Protocol, specifically affecting versions prior to 3.23.0. This flaw exists within the X11-based window management system where the application handles Remote Application Layer (RAIL) channel communications. The issue manifests when processing window management operations, particularly during min/max information handling, creating a scenario where memory safety is compromised through improper pointer management. The vulnerability stems from the fundamental race condition between concurrent threads operating on shared data structures without adequate synchronization mechanisms.
The technical flaw occurs in the `xf_SetWindowMinMaxInfo` function which processes window size constraints for remote desktop sessions. When `xf_rail_get_window` is called from within `xf_rail_server_min_max_info`, it retrieves a pointer to an `xfAppWindow` structure from the `railWindows` hash table without proper protection against concurrent modification. This unprotected access pattern creates a window where the main thread can execute a window deletion operation while another thread is still processing the RAIL channel data that references the same memory location. The dereference of the freed pointer results in undefined behavior that can potentially lead to memory corruption and arbitrary code execution.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a classic thread safety issue that can be exploited by remote attackers. The race condition allows for potential exploitation through carefully crafted RAIL channel communications that trigger the specific sequence of operations leading to the use-after-free scenario. Attackers could leverage this vulnerability to execute malicious code on systems running vulnerable versions of FreeRDP, particularly those serving as RDP servers or acting as RDP clients in environments where remote desktop access is prevalent. The vulnerability's exploitation potential is heightened by the fact that it occurs during normal RDP session operations, making it difficult to detect and prevent through standard network monitoring.
This vulnerability aligns with CWE-416, which describes the use of freed pointers, and demonstrates characteristics consistent with the ATT&CK technique T1059.007 for command and script interpreter execution through remote desktop protocols. The flaw represents a failure in memory management practices and concurrent programming patterns, where proper synchronization mechanisms should have been implemented to protect shared resources. The fix implemented in version 3.23.0 addresses the core issue by ensuring proper synchronization between threads accessing the `railWindows` hash table, preventing the scenario where a window deletion operation can occur while another thread holds a reference to the same memory location. Organizations should prioritize updating to version 3.23.0 or later to mitigate this vulnerability, while also implementing network segmentation and access controls to limit exposure to potential exploitation attempts.