FreeRDP EUVD-2026-102561

Exploitation requires the victim to run a FreeRDP client version 3.29.0 through 3.31.x on macOS or iOS (the audin_mac.m / audin_ios.m Apple audio-input backends) and to initiate an RDP connection to an attacker-controlled or compromised server that negotiates the audin (audio input) dynamic virtual channel. The specific trigger is a server-sent audin Open PDU carrying FramesPerPacket = 2^30, which wraps the FramesPerPacket * 2 * nChannels UINT32 computation. Limiting factors: only Apple (macOS/iOS) builds are affected (Linux/Windows backends are not in scope); the user must actively connect to the malicious server (UI:P / passive interaction), so there is no server-side or drive-by vector; and the audio-input channel must be in use.

This is a client-side heap out-of-bounds write (CWE-190 integer overflow) affecting only the macOS/iOS Apple audin backends of FreeRDP, triggered by a malicious or compromised RDP server. The provided CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H, 8.7 High) is internally consistent with the description: network reachable, low complexity, no privileges, but requiring passive user interaction (the victim must initiate an RDP connection to the attacker's server). The high VC/VI/VA reflect realistic potential for memory corruption leading to code execution on the client. No EPSS score, KEV listing, or POC is present in the input, so there is no public exploit identified at time of analysis and no evidence of active exploitation - the signals do not conflict, they simply all point to a serious-but-not-yet-weaponized client vulnerability. The key practical risk limiter is the reversed trust model: unlike server-side RDP flaws, exploitation requires luring a user to connect to a hostile server, which constrains mass exploitation and favors targeted or phishing-style delivery. Notably this bypasses the prior CVE-2026-91962 fix, indicating an incomplete patch that a motivated attacker could rediscover from the public GHSA advisory and diff. Priority should be elevated for organizations running FreeRDP-based clients on Apple platforms, but lower for environments that do not use the Apple audin audio-input path.

An attacker stands up a malicious RDP server (or compromises a legitimate one) and entices a macOS or iOS user to connect with a vulnerable FreeRDP client. During channel negotiation the server sends an audin Open PDU with FramesPerPacket set to 2^30, wrapping the UINT32 buffer-size multiplication and causing an undersized AudioQueueAllocateBuffer allocation followed by a heap out-of-bounds write, potentially leading to client-side code execution. No public POC is identified at time of analysis, though the published GHSA advisory provides enough detail to reconstruct the trigger.