---
title: "CVE-2026-54617: LaunchServer FileServerHandler has an unauthenticated path traversal issue"
url: https://erroneo.us/security/cve/CVE-2026-54617/
description: "CVE-2026-54617 (pro.gravit.launcher:launchserver-api (Maven)): GravitLauncher is an open-source Minecraft launcher based on sashok724's v3. Prior to 5.7.12…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-17
date_modified: 2026-09-18
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-54617"
kev: false
cvss: 9.8
epss: 0.02883
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-54617: LaunchServer FileServerHandler has an unauthenticated path traversal issue

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 2.9% , percentile 87: FIRST’s model estimates a 2.9% chance of exploitation activity in the next 30 days, higher than 87% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes pro.gravit.launcher:launchserver-api (Maven) <= 5.7.11, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

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/ecdsaid, .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.

## Affected packages

- Maven `pro.gravit.launcher:launchserver-api` <= 5.7.11 → fixed: none listed

## Affected products (CVE record)

- GravitLauncher Launcher: < 5.7.12

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 2.88% probability of exploitation activity in the next 30 days; percentile 87.

## Sources

- [GitHub Advisory GHSA-5g75-477j-2c2f](https://github.com/advisories/GHSA-5g75-477j-2c2f)
- [CVE.org record CVE-2026-54617](https://www.cve.org/CVERecord?id=CVE-2026-54617)
- [NVD entry CVE-2026-54617](https://nvd.nist.gov/vuln/detail/CVE-2026-54617)
- [github.com](https://github.com/GravitLauncher/Launcher/security/advisories/GHSA-5g75-477j-2c2f)
- [github.com](https://github.com/GravitLauncher/Launcher/commit/8114a1d4cfbcaab4c1c337d921597805d71dee3b)
- [github.com](https://github.com/GravitLauncher/Launcher/releases/tag/v5.7.12)

---
Source page: https://erroneo.us/security/cve/CVE-2026-54617/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt