CVE-2026-54617 GravitLauncher: Unauthenticated path traversal in LaunchServer FileServerHandler
Unauthenticated attackers can read sensitive files via path traversal, exposing keys and credentials to enable authentication bypass.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-54617?
CVE-2026-54617 is a critical path traversal vulnerability in GravitLauncher Launcher, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-54617?
2 open source packages ship an affected version, including pro.gravit.launcher:launchserver-api.
| Package | Affected | Fixed in |
|---|---|---|
pro.gravit.launcher:launchserver-api Maven | All versions to 5.7.11 | None |
pro.gravit.launcher:launchserver-api Maven | All versions to 5.7.11 | None |
How do I fix CVE-2026-54617?
No fix has been published for CVE-2026-54617 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-54617 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-54617 exists.
Public exploit code: 1 Nuclei template.
Sources
Also known as GHSA-5g75-477j-2c2f.