CVE-2023-42800: Buffer overflow due to use of `strcpy` in `performRtspHandshake`

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2023-12-14 · updated 2026-06-17
Weakness: CWE-120

Description

Moonlight-common-c contains the core GameStream client code shared between Moonlight clients. Moonlight-common-c is vulnerable to buffer overflow starting in commit 50c0a51b10ecc5b3415ea78c21d96d679e2288f9 due to unmitigated usage of unsafe C functions and improper bounds checking. A malicious game streaming server could exploit a buffer overflow vulnerability to crash a moonlight client, or achieve remote code execution (RCE) on the client (with insufficient exploit mitigations or if mitigations can be bypassed). The bug was addressed in commit 24750d4b748fefa03d09fcfd6d45056faca354e0.

Affected products

moonlight-stream Moonlight: from 8.4.0 through 8.5.0; from 10.10 through 11.0; 0.10.22
moonlight-stream moonlight-common-c: from 2022-11-04 before 2023-10-06 — fixed in 2023-10-06
moonlight-stream Moonlight Embedded: 2.6.0
moonlight-stream Moonlight Switch: from 0.13 through 0.13.3
moonlight-stream Moonlight Tv: from 1.5.4 through 1.5.27
moonlight-stream Moonlight Vita: from 0.9.2 through 0.9.3
moonlight-stream Moonlight Xbox: from 1.12.0 through 1.14.40

How to fix

Upgrade to a fixed version: moonlight-stream moonlight-common-c 2023-10-06. Check the vendor advisory for mitigations.

References

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