CVE-2026-109246 FreeRDP CVE debrief

Who should care

Defenders responsible for systems using FreeRDP's shadow server functionality should assess exposure and prioritize verification and updates to prevent potential exploitation. This includes operators, platform administrators, vulnerability management teams, and security teams who need to ensure the security and integrity of remote access and collaboration services.

Why it matters

Defenders should care about CVE-2026-109246 because it affects FreeRDP's shadow server functionality, potentially allowing authenticated clients to cause a denial of service. Systems using FreeRDP's shadow server should assess exposure and prioritize verification and updates to prevent potential exploitation.

• Potential denial of service due to process termination
• Potential disruption to viewer connections
• Need for verification and updates to prevent exploitation
• Possible impact on remote access and collaboration services

Technical summary

The vulnerability occurs in the freerdp-shadow-cli shadow server, where the frame id in a client's Frame Acknowledge PDU is stored without a range check. An authenticated client can acknowledge a frame id one greater than the last frame sent, causing shadow_encoder_create_frame_id() to divide by zero (SIGFPE) and terminate the process, disconnecting all viewers. This affects FreeRDP's shadow server functionality, potentially allowing authenticated clients to cause a denial of service. Systems using FreeRDP's shadow server should assess exposure and prioritize verification and updates to prevent potential exploitation.

Defensive priority

Defenders should prioritize verifying and updating FreeRDP installations to version 3.32.0 or later, especially for systems using the shadow server functionality.

Recommended defensive actions

• Verify and update FreeRDP installations to version 3.32.0 or later
• Review and restrict access to the shadow server functionality
• Monitor for and respond to potential exploitation attempts
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE Program record and NVD vulnerability detail provide official information about the vulnerability. The source item and supplemental sources offer additional context and vendor advisories. FreeRDP's shadow server functionality is impacted, and defenders should verify and update installations to version 3.32.0 or later. The vulnerability's scope and potential impact on remote access and collaboration services should be assessed.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.