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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| moonlight-stream | moonlight-qt | affected |
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Fixes
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References
History
Mon, 12 Oct 2026 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Moonlight Qt: Remote heap buffer overflow in Moonlight Qt H.264 SPS fixup path via crafted seq_parameter_set_id | |
| Weaknesses | CWE-787 | |
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| Metrics |
cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-10-12T21:25:03.303Z
Reserved: 2026-04-18T02:51:52.975Z
Link: CVE-2026-41210
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Weaknesses