CVE-2026-55827 FreeRDP CVE debrief

Who should care

Users of FreeRDP clients, especially those using versions prior to 3.27.1, should be aware of this vulnerability and take steps to mitigate it. Affected operators, platforms, vulnerability-management, and security teams should review the vulnerability and implement necessary security measures.

Technical summary

Prior to version 3.27.1, FreeRDP clients launched with the non-default /cache:codec:rfx option pass desktop stride and height to RemoteFX decoding for Cache Bitmap V3 data while allocating bitmap->data only for the smaller DstWidth and DstHeight in gdi_Bitmap_Decompress. This allows a malicious RDP server to trigger a heap out-of-bounds write with attacker-controlled offset and content. Defenders should review compensating controls for exposed systems while remediation is scheduled and verified.

Defensive priority

High

Recommended defensive actions

• Update FreeRDP to version 3.27.1 or later
• Avoid using the /cache:codec:rfx option unless necessary
• Monitor for suspicious RDP activity
• Implement additional security measures such as network segmentation and access controls
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-07-10T20:16:48.060Z and has not been modified since then. The NVD entry is currently being reviewed. Evidence limits suggest that FreeRDP clients launched with the non-default /cache:codec:rfx option are vulnerable to a heap out-of-bounds write. Defenders should verify affected product deployments and review official advisories for scope, severity, and vendor guidance.

Official resources