Medium severity4.3NVD Advisory· Published Aug 1, 2026· Updated Sep 29, 2026
CVE-2026-67303
CVE-2026-67303
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).
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Affected products
2Patches
Vulnerability mechanics
References
4- github.com/FreeRDP/FreeRDP/commit/1cc783d4c78bd2f66d3a8582dfe70a663d141444nvdPatch
- github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493fnvdPatch
- www.vulncheck.com/advisories/freerdp-before-denial-of-service-via-serial-devicecontrolnvdPatchThird Party Advisory
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pfxq-3qmw-8vjxnvdMitigationVendor Advisory
News mentions
1- Freerdp: 21 Vulnerabilities Disclosed Together, Patch Released in 3.29.0Vypr Intelligence · Aug 2, 2026