CVE-2026-24677 in FreeRDP
Summary
by MITRE • 02/09/2026
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.22.0, ecam_encoder_compress_h264 trusts server-controlled dimensions and does not validate the source buffer size, leading to an out-of-bounds read in sws_scale. This vulnerability is fixed in 3.22.0.
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Analysis
by VulDB Data Team • 02/25/2026
The vulnerability identified as CVE-2026-24677 affects FreeRDP, an open-source implementation of Microsoft's Remote Desktop Protocol that enables remote desktop connections across various platforms. This security flaw exists in versions prior to 3.22.0 and represents a critical out-of-bounds read condition that can potentially be exploited by remote attackers. The vulnerability specifically manifests within the ecam_encoder_compress_h264 function which processes video compression for remote desktop sessions, making it particularly dangerous in networked environments where remote desktop services are actively utilized.
The technical root cause of this vulnerability lies in the improper validation of server-controlled parameters within the video encoding pipeline. When FreeRDP processes video data for transmission, the ecam_encoder_compress_h264 function blindly trusts dimensional parameters provided by the remote server without performing adequate validation checks. This lack of input sanitization creates an opportunity for attackers to manipulate the source buffer size parameters, leading to a scenario where sws_scale function attempts to read beyond the allocated memory boundaries. The vulnerability is categorized as an out-of-bounds read according to CWE-125, which represents a fundamental memory safety issue where a program reads memory beyond the intended buffer limits, potentially exposing sensitive data or causing application crashes.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially allow attackers to extract sensitive information from memory locations adjacent to the compromised buffer. When an attacker successfully exploits this vulnerability, they can potentially read arbitrary memory contents that may include authentication credentials, session tokens, or other confidential data stored in memory. The attack vector requires a remote server to initiate a malicious connection, making it particularly concerning for organizations that rely on FreeRDP for secure remote access solutions. This vulnerability affects the integrity and confidentiality of remote desktop sessions, as attackers could potentially intercept or manipulate data transmitted through the affected implementation, undermining the security posture of systems relying on FreeRDP for remote desktop connectivity.
The fix implemented in version 3.22.0 addresses this vulnerability by introducing proper validation mechanisms for server-controlled dimensions and source buffer size parameters within the ecam_encoder_compress_h264 function. This remediation aligns with security best practices recommended by the ATT&CK framework under the technique of T1059.007 for command and scripting interpreter, as it prevents malicious input from causing unintended memory access patterns. Organizations should prioritize immediate upgrade to FreeRDP version 3.22.0 or later to mitigate this vulnerability. Additional mitigations include implementing network segmentation to limit exposure of FreeRDP services, enabling strict access controls for remote desktop connections, and monitoring network traffic for suspicious patterns that might indicate exploitation attempts. Security teams should also consider implementing intrusion detection systems capable of identifying anomalous behavior in remote desktop protocol implementations, as this vulnerability could potentially serve as a stepping stone for more sophisticated attacks targeting the underlying network infrastructure.