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Moonlight Common CApplication · Moonlight Stream

CVE-2023-42800

HIGH · 8.8 CVSS v3.1 Published 2023-12-14
Fix available
A fix is available. Upgrade to 2023-10-06 or later.
See remediation →
95/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-120

A fixed-size buffer is filled without checking the length of the incoming data, so it overflows into neighbouring memory. This is the classic overflow attackers use to overwrite return addresses and hijack execution. The fix is strict length checks and safe, bounded string and memory functions.

General guidance for the classic buffer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Moonlight Common CApplication
Affected:>= 2022-11-04, < 2023-10-06
MoonlightApplication
Affected:>= 8.4.0, <= 8.5.0>= 10.10, <= 11.0= 0.10.22
Moonlight EmbeddedApplication
Affected:= 2.6.0
Moonlight XboxApplication
Affected:>= 1.12.0, <= 1.14.40
Moonlight TvApplication
Affected:>= 1.5.4, <= 1.5.27
Moonlight SwitchApplication
Affected:>= 0.13, <= 0.13.3
Moonlight VitaApplication
Affected:>= 0.9.2, <= 0.9.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2023-10-06 or later
Fixed in 2023-10-06
Vendor patch github.com →
Recommended fix High confidence

Moonlight Common C version >= 2023-10-06; or respective client versions >= 2023-10-06 incorporating fixed library

  1. Identify which Moonlight client variant you are using (Moonlight, Moonlight Embedded, Moonlight Xbox, Moonlight Tv, Moonlight Switch, or Moonlight Vita)
  2. For Moonlight Common C users: Upgrade to version 2023-10-06 or later which contains the fixed code
  3. For Moonlight Windows/macOS/iOS/Android clients: Upgrade to a version newer than the affected ranges (8.5.0, 11.0, or 0.10.22+) that incorporates the patched moonlight-common-c library
  4. For Moonlight Embedded (version 2.6.0): Upgrade to a newer version that includes the patched moonlight-common-c
  5. For Moonlight Xbox (versions 1.12.0-1.14.40): Upgrade to version 1.14.41 or later
  6. For Moonlight Tv (versions 1.5.4-1.5.27): Upgrade to version 1.5.28 or later
  7. For Moonlight Switch (versions 0.13-0.13.3): Upgrade to version 0.13.4 or later
  8. For Moonlight Vita (versions 0.9.2-0.9.3): Upgrade to version 0.9.4 or later

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-42800 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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