CVE-2026-91963 FreeRDP CVE debrief

Who should care

Defenders responsible for systems using FreeRDP should assess exposure and prioritize verification of versions, as the vulnerability could aid exploitation of other vulnerabilities.

Why it matters

Defenders should prioritize verifying FreeRDP versions and assessing exposure, as the vulnerability allows remote disclosure of uninitialized heap memory, potentially aiding exploitation of other vulnerabilities.

• Remote disclosure of uninitialized heap memory
• Potential aid in exploitation of other vulnerabilities
• Defeat of ASLR protections in FreeRDP
• Verification of FreeRDP versions and exposure

Technical summary

FreeRDP versions before 3.31.0 contain an uninitialized heap memory disclosure vulnerability in the urbdrc USB redirection channel. A malicious RDP server can induce failing USB transfers to read uninitialized heap memory from the client, defeating ASLR and enabling remote code execution when chained with memory corruption vulnerabilities. The vulnerability allows remote disclosure of uninitialized heap memory, potentially aiding exploitation of other vulnerabilities. Defenders should prioritize verifying FreeRDP versions and assessing exposure.

Defensive priority

Defenders should prioritize verifying FreeRDP versions and assessing exposure, as the vulnerability allows remote disclosure of uninitialized heap memory, potentially aiding exploitation of other vulnerabilities.

Recommended defensive actions

• Verify FreeRDP versions and assess exposure
• Implement compensating controls to limit potential exploitation
• Monitor for suspicious activity related to the urbdrc USB redirection channel
• Review vendor advisories for additional guidance
• Conduct vulnerability scanning to identify exposed systems
• Prioritize patching of vulnerable FreeRDP deployments
• Track exceptions and retest remediated assets

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description and affected versions. Vendor advisories and third-party reports offer additional context. The vulnerability affects FreeRDP versions before 3.31.0 and involves an uninitialized heap memory disclosure in the urbdrc USB redirection channel. Defenders should verify FreeRDP versions and assess exposure to this 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.