What’s Vulnerable › Vulnerabilities

CVE-2023-42801: Stack buffer overflow due to `strcpy` into fixed size buffer in `extractVersionQuadFromString`

• Severity: high (CVSS 7.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.9% 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 f57bd745b4cbed577ea654fad4701bea4d38b44c. A malicious game streaming server could exploit a buffer overflow vulnerability to crash a moonlight client. Achieving RCE is possible but unlikely, due to stack canaries in use by modern compiler toolchains. The published binaries for official clients Qt, Android, iOS/tvOS, and Embedded are built with stack canaries, but some unofficial clients may not use stack canaries. This vulnerability takes place after the pairing process, so it requires the client to be tricked into pairing to a malicious host. It is not possible to perform using a man-in-the-middle due to public key pinning that takes place during the pairing process. The bug was addressed in commit b2497a3918a6d79808d9fd0c04734786e70d5954.

Affected products

• moonlight-stream Moonlight: before 9.0.0; before 12.0; before 0.10.23 — fixed in 0.10.23, 12.0, 9.0.0
• moonlight-stream moonlight-common-c: from 2016-10-05 before 2023-10-06 — fixed in 2023-10-06
• moonlight-stream Moonlight Embedded: before 2.6.1 — fixed in 2.6.1
• moonlight-stream Moonlight Qt/Pc: through 5.0.0
• moonlight-stream Moonlight Switch: before 0.13.4 — fixed in 0.13.4
• moonlight-stream Moonlight Tv: before 1.6.0 — fixed in 1.6.0
• moonlight-stream Moonlight Vita: all versions
• moonlight-stream Moonlight Xbox: through 1.14.5

How to fix

Upgrade to a fixed version: moonlight-stream Moonlight 0.10.23, 12.0, 9.0.0; moonlight-stream moonlight-common-c 2023-10-06; moonlight-stream Moonlight Embedded 2.6.1; moonlight-stream Moonlight Switch 0.13.4; moonlight-stream Moonlight Tv 1.6.0. Check the vendor advisory for mitigations.

References

• https://github.com/moonlight-stream/moonlight-common-c/blob/c1744de06938b5a5c8897a705be1bc6508dc7580/src/Misc.c#L82-L88
• https://github.com/moonlight-stream/moonlight-common-c/commit/b2497a3918a6d79808d9fd0c04734786e70d5954
• https://github.com/moonlight-stream/moonlight-common-c/commit/f57bd745b4cbed577ea654fad4701bea4d38b44c
• https://github.com/moonlight-stream/moonlight-common-c/security/advisories/GHSA-f3h8-j898-5h5v
• https://github.com/moonlight-stream/moonlight-common-c/blob/c1744de06938b5a5c8897a705be1bc6508dc7580/src/Misc.c#L82-L88
• https://github.com/moonlight-stream/moonlight-common-c/commit/b2497a3918a6d79808d9fd0c04734786e70d5954
• https://github.com/moonlight-stream/moonlight-common-c/commit/f57bd745b4cbed577ea654fad4701bea4d38b44c
• https://github.com/moonlight-stream/moonlight-common-c/security/advisories/GHSA-f3h8-j898-5h5v

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