CVE-2026-109677 FreeRDP CVE debrief

Who should care

Defenders responsible for FreeRDP deployments should assess exposure and prioritize patching to prevent potential memory leaks and RCE exploits. This includes reviewing and updating vulnerability management processes, ensuring that FreeRDP versions are verified and patched, and monitoring for suspicious RDP activity. Additionally, defenders should review compensating controls for exposed systems and track exceptions and retest remediated assets.

Why it matters

Defenders should prioritize verifying FreeRDP versions and applying patches to prevent potential memory leaks and RCE exploits.

• Malicious RDP servers can leak heap memory bit-by-bit
• ASLR can be defeated aiding RCE exploits
• Query timing can be used as an oracle

Technical summary

FreeRDP 2.0.0-beta1 before 3.28.0 contains an out-of-bounds read vulnerability in smartcard_LocateCardsByATRA_Call. The vulnerability is caused by the ATR pattern cbAtr byte count not being capped, allowing malicious RDP servers to send crafted ATR mask arrays. This could potentially allow attackers to leak heap memory bit-by-bit and defeat ASLR, aiding RCE exploits. Defenders should prioritize verifying FreeRDP versions and applying patches to prevent potential memory leaks and RCE exploits. The vulnerability can be exploited by sending crafted ATR mask arrays to use query timing as an oracle.

Defensive priority

Defenders should prioritize verifying FreeRDP versions and applying patches, as the vulnerability allows malicious RDP servers to leak heap memory.

Recommended defensive actions

• Verify FreeRDP versions and apply patches
• Restrict access to RDP servers
• Monitor for suspicious RDP activity
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions and retest remediated assets
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the out-of-bounds read vulnerability in FreeRDP 2.0.0-beta1 before 3.28.0. The vulnerability is caused by the ATR pattern cbAtr byte count not being capped, allowing malicious RDP servers to send crafted ATR mask arrays. The CVE Program record and NVD detail page provide additional information on the vulnerability.

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.