Full Report
Microsoft has confirmed that the August 2025 security updates are causing severe lag and stuttering issues with NDI streaming software on some Windows 10 and Windows 11 systems. [...]
Analysis Summary
# Vulnerability: Severe NDI Streaming Issues Post August 2025 Windows Updates
## CVE Details
- CVE ID: N/A (This is a functional defect/bug report, not a traditional security CVE)
- CVSS Score: N/A
- CWE: N/A
## Affected Systems
- Products: Microsoft Windows 10, Windows 11 (specifically versions receiving August 2025 security updates)
- Versions: Windows 11 24H2, Windows 10 21H2/22H2
- Configurations: Systems using Network Device Interface (NDI) for streaming or audio/video transfer, particularly when 'Display Capture' is enabled on the source PC, and using RUDP connections. Affected updates are KB5063878 (Win 11) and KB5063709 (Win 10).
## Vulnerability Description
The August 2025 cumulative security updates released by Microsoft are causing significant performance degradation—severe stuttering, lag, and choppy audio/video—in streaming applications utilizing NDI (Network Device Interface). The NDI team confirmed that the buggy Windows updates cause NDI traffic to drop unexpectedly, specifically when using **RUDP** connections. Performance using standard UDP or Single-TCP remains unaffected.
## Exploitation
- Status: Not a security vulnerability; functional defect.
- Complexity: N/A
- Attack Vector: N/A (Impacts legitimate application functionality)
## Impact
- Confidentiality: No direct impact.
- Integrity: Degraded integrity of real-time video/audio streams.
- Availability: Reduced availability/usability of NDI streaming functionality.
## Remediation
### Patches
- Microsoft is investigating the bug. No specific security update patch is listed *yet* to explicitly fix this NDI issue, separate from the emergency fixes released for other, noted bugs associated with KB5063878/KB5063709.
### Workarounds
The NDI team provided a workaround to circumvent the RUDP issue:
1. Download and install the free **NDI Tools pack**.
2. Launch the **NDI Access Manager** app.
3. Go to the **Advanced tab**.
4. Change **Receive Mode** to **Single TCP** or **UDP**.
5. Repeat this configuration change on all affected computers.
## Detection
- Indicators of Compromise: Severe stuttering, lag, or choppy audio/video specifically noted when using NDI streaming software (e.g., OBS) after installing the August 2025 updates.
- Detection methods and tools: Monitoring NDI traffic logs for unexpected connection drops, particularly over RUDP. Checking system event logs for correlated errors following the installation of KB5063878 or KB5063709.
## References
- Vendor advisories:
- Microsoft Windows Release Health Update (Related issue confirmation)
- NDI Team FAQ/Forums (Workaround details)
- Relevant links - defanged:
- hxxps://learn.microsoft.com/en-us/windows/release-health/status-windows-11-24h2#3639msgdesc
- hxxps://docs.ndi.video/all/faq/common-issues/traffic-drops-after-windows-update
- hxxps://www.bleepingcomputer.com/news/microsoft/microsoft-august-windows-updates-cause-severe-ndi-streaming-issues/ (Source Article)