launcher - Path Traversal (CVE-2026-54617)
Description
GravitLauncher is an open-source Minecraft launcher based on sashok724's v3. Prior to 5.7.12, an unauthenticated remote actor can send a raw HTTP request target without a leading slash to the default LaunchServer file server on port 9274. FileServerHandler.channelRead0 in components/launchserver/src/main/java/pro/gravit/launchserver/socket/handlers/fileserver/FileServerHandler.java strips the first request-target character and resolves the remaining path against updatesDir without re-normalizing and verifying containment. This leaves parent-directory components in a no-leading-slash request and allows reading any file accessible to the LaunchServer process, including .keys/ecdsa_id, .keys/legacySalt, and LaunchServer.json. Disclosure of those files can expose signing keys, refresh-token material, and database credentials, enabling forged administrative access tokens and full authentication bypass. A normalizing L7 proxy may block the primary request form, but direct exposure and L4/TCP proxies remain affected, and netty.fileServerEnabled is enabled by default. This issue is fixed in 5.7.12.
psychologyCrowdSec Analysis
CVE-2026-54617 is a critical path traversal vulnerability in GravitLauncher versions prior to 5.7.12 that allows unauthenticated remote attackers to read files accessible to the LaunchServer process. Exposed signing keys, token material, or database credentials could enable forged administrative tokens and authentication bypass, potentially leading to full system compromise.
CrowdSec has been tracking this vulnerability and its exploits since 20th of October 2026.
CrowdSec has not observed any significant exploitation activity targeting CVE-2026-54617 across its network. As a result, no community-driven trend analysis is available for this vulnerability at this time.
Observed exploitation attempts send unauthenticated GET requests with a request target such as ../../.keys/ecdsa_id to the LaunchServer file service, typically on port 9274. The missing leading slash enables path traversal outside the updates directory to read files accessible to the server process.
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| Event | Date |
|---|---|
| CVE Published | 2026-09-17 |
| Rule Released | 2026-10-20 |
Related Weaknesses
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.
Remediation & Protection
External References
- https://github.com/GravitLauncher/Launcher/security/advisories/GHSA-5g75-477j-2c2f
- https://github.com/GravitLauncher/Launcher/releases/tag/v5.7.12
- https://github.com/GravitLauncher/Launcher/commit/8114a1d4cfbcaab4c1c337d921597805d71dee3b
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-54617.yaml