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
Affects freerdpSource GCVE Database
Not known to be exploited · CVSS 4.3 Medium : upgrade to 3.29.0 when convenient.
Data as of 31 Oct 2026, 08:20 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.29.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:LExploitation evidence
Disclosed: evidence found.
CVE published 1 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade freerdp/FreeRDP to 3.29.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubfreerdp/FreeRDPpkg:github/freerdp/FreeRDPOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available in FreeRDP version 3.29.0. Users should upgrade to version 3.29.0 or later to remediate this vulnerability. No vendor advisory was provided to indicate alternative mitigations or temporary fixes.
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).
References
- github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pfxq-3qmw-8vjx (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-67303 (opens in a new tab)
- github.com/FreeRDP/FreeRDP/commit/1cc783d4c78bd2f66d3a8582dfe70a663d141444 (opens in a new tab)
- github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f (opens in a new tab)
- vulncheck.com/advisories/freerdp-before-denial-of-service-via-serial-devicecontrol (opens in a new tab)
- ubuntu.com/security/CVE-2026-67303 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-67303 (opens in a new tab)