{"id":"CVE-2026-67303","title":"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","summary":"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 serv…","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","cwe":["CWE-617"],"vendor":"freerdp","product":"freerdp","affected":["freerdp < 3.29.0"],"patched":["freerdp 3.29.0"],"published":"2026-08-01","updated":"2026-09-29","sourceUpdated":"2026-09-29T16:17:16.917","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-67303","references":[{"url":"https://github.com/FreeRDP/FreeRDP/commit/1cc783d4c78bd2f66d3a8582dfe70a663d141444","label":"disclosure@vulncheck.com"},{"url":"https://github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f","label":"disclosure@vulncheck.com"},{"url":"https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pfxq-3qmw-8vjx","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/freerdp-before-denial-of-service-via-serial-devicecontrol","label":"disclosure@vulncheck.com"}],"tags":["nvd"],"epss":0.00418,"epssPercentile":0.35943,"ingestedAt":"2026-08-02T07:18:01.416Z","slug":"CVE-2026-67303","body":"## Overview\n\nFreeRDP 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).\n\n## Affected\n\n- `freerdp < 3.29.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `freerdp 3.29.0`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}