CVE-2026-67303

FreeRDP before 3.29.0 Denial of Service via serial DeviceControl

MEDIUM
4.3
CVSS Score
Published: August 1, 2026 at 12:22 PM UTC
Updated: September 29, 2026 at 04:17 PM UTC
1 product affected across 1 vendorFreeRDP

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

FreeRDP before 3.29.0 contains a reachable assertion (WINPR_ASSERT(OutputBufferLength == BytesReturned)) in serial_process_irp_device_control() in channels/serial/client/serial_main.c. When serial device redirection is enabled and a server-controlled IRP_MJ_DEVICE_CONTROL request specifies an unsupported IOCTL with a non-zero OutputBufferLength, CommDeviceIoControl() can fail with BytesReturned = 0, causing the mismatch to trigger the assertion and abort the client process (denial of service).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.29.0
Vendor states this is fixed in 3.29.0 (unaffected)

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-617

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