FreeRDP HTTP Response Chunked Memory Exhaustion

Executive Summary

FreeRDP before version 3.29.0 has a flaw where it does not properly enforce the RESPONSE_SIZE_LIMIT when handling Transfer-Encoding: chunked HTTP responses. This allows attackers controlling a malicious RD Gateway endpoint to send excessively large chunked response bodies, consuming client memory resources without triggering the configured size limit.

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Detection Guidance

Detecting this vulnerability requires monitoring for oversized chunked HTTP responses from RD Gateway endpoints. Check FreeRDP logs for memory exhaustion errors or HTTP response size violations. Use network monitoring tools like Wireshark to inspect HTTP responses for chunked transfer encoding exceeding expected limits.

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Impact Analysis

This vulnerability can lead to denial-of-service conditions on affected systems by exhausting available memory resources. Users connecting to a compromised RD Gateway may experience crashes, slowdowns, or system instability due to the excessive memory consumption caused by oversized responses.

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Mitigation Strategies

Upgrade FreeRDP to version 3.29.0 or later to address the vulnerability. Disable RD Gateway endpoints if not required. Implement network-level restrictions to block oversized HTTP responses. Monitor for unusual memory usage patterns on client systems.

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