EXPOSURES › CVE-2026-63633
CVE-2026-63633
CRITICALA malicious RDP server exploiting a heap corruption flaw in FreeRDP can crash the client and potentially execute arbitrary code.
CVE-2026-63633 allows a remote attacker to corrupt the client heap and potentially execute code by sending a specially crafted RDP stream. DIB organizations must patch FreeRDP to 3.28.0 immediately, as this flaw could be leveraged for remote code execution in unpatched environments.
Shame score — A critical RCE vulnerability in a widely used RDP client library that was actively exploited in the wild, requiring urgent patching to prevent remote code execution.
▸ RECOMMENDED ACTION Remote code execution — patch the affected products on priority.
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.28.0, freerdp_dsp_decode_opus in libfreerdp/codec/dsp.c calls Stream_EnsureRemainingCapacity on context->common.buffer even though opus_decode writes decoded PCM into the caller-supplied out stream. A malicious RDP server that negotiates WAVE_FORMAT_OPUS with a client built with WITH_OPUS enabled and WITH_DSP_FFMPEG disabled can make libopus write a large decoded frame beyond the 4096-byte StreamPool_Take destination used by channels/rdpsnd/client/rdpsnd_main.c. This can corrupt the client heap, crash the client, and may permit code execution. This issue is fixed in version 3.28.0.