CVE-2026-41210 Details
Description
Moonlight Qt is a GameStream client for Windows, macOS, Linux, and Steam Link. In version 6.1.0 and earlier, after a victim initiates a streaming session to a malicious host, the host can send a crafted H.264 SPS NAL when Moonlight selects a decoder path that does not advertise CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC. The SPS fixup path in app/streaming/video/ffmpeg.cpp parses the server-provided data with h264bitstream, where attacker-controlled seq_parameter_set_id is used to index the 32-entry sps_table without validation. A value of 32 or greater causes an out-of-bounds write and remote heap corruption in the Moonlight client. The demonstrated impact is a reliable client crash, while code execution is not established. This issue is fixed in version 6.2.0.
A remote heap buffer overflow vulnerability has been identified in Moonlight Qt, a GameStream client available on Windows, macOS, Linux, and Steam Link. This vulnerability exists in versions through 6.1.0. The issue arises when a victim streams to a malicious host that sends a specially crafted H.264 Sequence Parameter Set (SPS) NAL unit. If Moonlight's decoder path does not support reference frame invalidation, the application processes the SPS using an unvalidated sequence parameter set ID. This oversight allows for out-of-bounds writes, leading to heap corruption and a crash of the Moonlight client. While the crash has been reliably reproduced, there is currently no established exploit for arbitrary code execution.
Users can upgrade to Moonlight Qt version 6.2.0 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 12, 2026CISA-ADP
Assessed Oct 13, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-787 | Out-of-bounds Write | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Moonlight Qt | <= 6.1.0 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 13, 2026 | CVE Modified | CISA-ADP |
| Oct 12, 2026 | New CVE Received | [email protected] |