CVE-2026-91961Network attack vectorHinoki check available

Client crash via unchecked URBDRC buffer size

Published Sep 15, 2026 · Updated Sep 15, 2026

Denial of service in FreeRDP before 3.31.0 allows remote attackers to terminate a client via a crafted URBDRC control-transfer request. The URBDRC parser accepts an OutputBufferSize of 65536 and forwards it to the libusb backend, where a WINPR_ASSERT requires a 16-bit value and aborts the process. The client must connect to a malicious RDP server with URBDRC, libusb, and assertions enabled; impact is limited to that client-process crash.

CVSS severityUnavailable
Unscored
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Denial of service in FreeRDP before 3.31.0 allows remote attackers to terminate a client via a crafted URBDRC control-transfer request. The URBDRC parser accepts an OutputBufferSize of 65536 and forwards it to the libusb backend, where a WINPR_ASSERT requires a 16-bit value and aborts the process. The client must connect to a malicious RDP server with URBDRC, libusb, and assertions enabled; impact is limited to that client-process crash.

The record

CVE
CVE-2026-91961
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.31.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=0 <3.31.0

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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