CVE-2026-54617

An unauthenticated path traversal in the LaunchServer HTTP file server (FileServerHandler) lets any remote actor read any file readable by the LaunchServer process (e.g. ../../../../etc/passwd). This is a generic arbitrary-file-read primitive, so the fix must address the traversal itself, not any specific file.

The readable files include the server's own secrets, which turns this from information disclosure into full compromise: the ECDSA private key that signs access JWTs (.keys/ecdsa_id), the refresh-token salt (.keys/legacySalt), and LaunchServer.json (database credentials). With the signing key an attacker mints a valid access token for any account, including admins. That is a full authentication bypass. Pre-auth, default config, port 9274.

Affected: GravitLauncher LaunchServer ≤ 5.7.11 (the LaunchServer application; the published pro.gravit.launcher:*-api Maven artifacts do not contain the vulnerable code).

Details

In FileServerHandler.channelRead0:

path = Paths.get(IOHelper.getPathFromUrlFragment(uri)).normalize().toString().substring(1); // line 194
File file = base.resolve(path).toFile();                                                     // line 200 - no second normalize()

substring(1) blindly strips a leading slash, assuming the request-target always starts with /. Netty's HttpServerCodec accepts a request-target without a leading slash verbatim (decoderResult().isSuccess() == true). For such a target, normalize() cannot collapse the leading .., substring(1) turns ../ into ./ (leaving the remaining ..), and base.resolve(path), which is not re-normalized, resolves outside updatesDir.

file.isHidden() (line 201) is checked only on the final path component, so targets that don't start with a dot (ecdsa_id, rsa_id, legacySalt, LaunchServer.json) are served even with showHiddenFiles=false.

The file server is enabled by default (netty.fileServerEnabled=true) and bound to 0.0.0.0:9274. No auth handler precedes FileServerHandler; WebSocketServerProtocolHandler("/api") forwards non-WebSocket / non-/api requests down to it, so the attack is a plain HTTP GET (no WebSocket).

PoC

Reproduced on a from-source build of v5.7.11 (Netty 4.2.12).
Must use a raw socket. curl/browsers/HTTP libraries normalize the path and prepend /, hitting the safe branch (false "not reproducible").

printf 'GET ../../.keys/ecdsa_id HTTP/1.1\r\nHost: x\r\n\r\n' | nc <host> 9274

Returns the raw ECDSA private-key bytes. Same for ../../.keys/rsa_id, ../../.keys/legacySalt, ../../LaunchServer.json. %2e%2e/... (no leading slash) also works. Depth-robust arbitrary read: ../../../../../../etc/passwd.
Control (confirms the root cause): GET /../../.keys/ecdsa_id (WITH leading slash) → 404. Only the no-leading-slash form escapes.

Unauthenticated remote read of any file the process can access. What that exposes:

• .keys/ecdsa_id: the key that signs access JWTs. With it, an attacker mints a valid token for any account, including admins, so this is a full authentication bypass.
• .keys/legacySalt: lets an attacker forge refresh tokens.
• LaunchServer.json: database credentials.
• Any other file readable by the process (config, logs, system files).

Deployment note: a normalizing L7 reverse proxy (stock nginx location / { proxy_pass ...; }) rejects the no-leading-slash request (400) and collapses leading-slash traversal, blocking the primary vector. But the default bind is 0.0.0.0:9274, so protection relies on firewalling the backend port; L4/TCP proxies (HAProxy TCP, nginx stream, CF Spectrum) and direct exposure remain exploitable.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-54617 has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. Re-normalize() after base.resolve(path) and verify resolved.startsWith(base).
2. Reject request-targets that don't start with / (400).
3. Default-bind to 127.0.0.1; store .keys outside updatesDir.

1. What is CVE-2026-54617? CVE-2026-54617 is a critical-severity path traversal vulnerability in pro.gravit.launcher:launchserver-api (maven), affecting versions <= 5.7.11. No fixed version is listed yet. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-54617? CVE-2026-54617 has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pro.gravit.launcher:launchserver-api are affected by CVE-2026-54617? pro.gravit.launcher:launchserver-api (maven) versions <= 5.7.11 is affected.
4. Is there a fix for CVE-2026-54617? No fixed version is listed for CVE-2026-54617 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2026-54617 exploitable, and should I be worried? Whether CVE-2026-54617 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54617 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54617? No fixed version is listed yet. In the interim: Resolve the canonical path after applying any user-supplied input, and verify it remains within the intended directory before accessing it.