Uninitialized Memory Disclosure in FreeRDP

Executive Summary

CVE-2026-109948 is a memory disclosure vulnerability in FreeRDP versions 3.0.0 through 3.31.0. It occurs in the smartcard redirection feature when handling SCardTransmit requests. A malicious RDP server can send a request with an invalid card handle and non-zero receive length, causing the client to serialize up to 66,560 uninitialized heap bytes into the response. This exposes sensitive memory contents to the attacker.

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Detection Guidance

To detect this vulnerability, monitor FreeRDP versions between 3.0.0 and 3.31.0. Check system logs for smartcard redirection events or unusual memory serialization patterns. Use network monitoring tools to inspect RDP traffic for SCardTransmit requests with invalid card handles and non-zero receive lengths.

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Impact Analysis

If you connect to a malicious RDP server with smartcard redirection enabled, the server could read uninitialized memory from your FreeRDP client. This may expose sensitive data stored in memory, though no specific secrets were reliably recovered. The impact is limited to confidentiality loss of memory contents.

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Compliance Impact

This vulnerability could potentially violate compliance requirements under GDPR or HIPAA by exposing sensitive data through memory disclosure. Organizations using FreeRDP with smartcard redirection may need to assess the risk of unauthorized memory access and implement mitigations like upgrading to patched versions.

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Mitigation Strategies

Upgrade FreeRDP to version 3.32.0 or later immediately. Disable smartcard redirection if not required. Avoid connecting to untrusted RDP servers. Monitor vendor advisories for additional patches or mitigations.

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