Vulnerability-Lookup

CVE-2026-54617 (GCVE-0-2026-54617)

Vulnerability from cvelistv5 – Published: 2026-09-17 18:34 – Updated: 2026-09-18 18:33

Title

GravitLauncher: Unauthenticated path traversal in LaunchServer FileServerHandler

Summary

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.

Severity

9.8 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-18 17:32 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
CWE-522 - Insufficiently Protected Credentials

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/GravitLauncher/Launcher/securi…	x_refsource_CONFIRM
https://github.com/GravitLauncher/Launcher/commit…	x_refsource_MISC
https://github.com/GravitLauncher/Launcher/releas…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
GravitLauncher	Launcher	Affected: < 5.7.12	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-54617

Vulnerability from fkie_nvd - Published: 2026-09-17 19:16 - Updated: 2026-09-17 19:16

Severity

9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/GravitLauncher/Launcher/commit/8114a1d4cfbcaab4c1c337d921597805d71dee3b
	security-advisories@github.com	https://github.com/GravitLauncher/Launcher/releases/tag/v5.7.12
	security-advisories@github.com	https://github.com/GravitLauncher/Launcher/security/advisories/GHSA-5g75-477j-2c2f

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Launcher",
          "vendor": "GravitLauncher",
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  ],
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  "lastModified": "2026-09-17T19:16:51.003",
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GHSA-5G75-477J-2C2F

Vulnerability from github – Published: 2026-07-02 20:49 – Updated: 2026-07-02 20:49

Summary

LaunchServer FileServerHandler has an unauthenticated path traversal issue

Details

Summary

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.

Impact

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.

Suggested fix

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

Severity

9.8 (Critical)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "pro.gravit.launcher:launchserver-api"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "5.7.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54617"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200",
      "CWE-22",
      "CWE-522"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-02T20:49:18Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "### Summary\nAn 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.\n\nThe readable files include the server\u0027s 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.\n\n**Affected:** GravitLauncher LaunchServer \u2264 5.7.11 (the LaunchServer application; the published `pro.gravit.launcher:*-api` Maven artifacts do not contain the vulnerable code).\n\n### Details\nIn `FileServerHandler.channelRead0`:\n\n```java\npath = Paths.get(IOHelper.getPathFromUrlFragment(uri)).normalize().toString().substring(1); // line 194\nFile file = base.resolve(path).toFile();                                                     // line 200 - no second normalize()\n```\n\n`substring(1)` blindly strips a leading slash, assuming the request-target always starts with `/`. Netty\u0027s `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`.\n\n`file.isHidden()` (line 201) is checked only on the final path component, so targets that don\u0027t start with a dot (`ecdsa_id`, `rsa_id`, `legacySalt`, `LaunchServer.json`) are served even with `showHiddenFiles=false`.\n\nThe 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).\n\n### PoC\nReproduced on a from-source build of v5.7.11 (Netty 4.2.12).\n**Must use a raw socket.** curl/browsers/HTTP libraries normalize the path and prepend `/`, hitting the safe branch (false \"not reproducible\").\n\n```\nprintf \u0027GET ../../.keys/ecdsa_id HTTP/1.1\\r\\nHost: x\\r\\n\\r\\n\u0027 | nc \u003chost\u003e 9274\n```\n\nReturns 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`.\nControl (confirms the root cause): `GET /../../.keys/ecdsa_id` (WITH leading slash) \u2192 404. Only the no-leading-slash form escapes.\n\n### Impact\nUnauthenticated remote read of any file the process can access. What that exposes:\n- `.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.\n- `.keys/legacySalt`: lets an attacker forge refresh tokens.\n- `LaunchServer.json`: database credentials.\n- Any other file readable by the process (config, logs, system files).\n\nDeployment 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.\n\n### Suggested fix\n1. Re-`normalize()` after `base.resolve(path)` and verify `resolved.startsWith(base)`.\n2. Reject request-targets that don\u0027t start with `/` (400).\n3. Default-bind to `127.0.0.1`; store `.keys` outside `updatesDir`.",
  "id": "GHSA-5g75-477j-2c2f",
  "modified": "2026-07-02T20:49:18Z",
  "published": "2026-07-02T20:49:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/GravitLauncher/Launcher/security/advisories/GHSA-5g75-477j-2c2f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/GravitLauncher/Launcher"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "LaunchServer FileServerHandler has an unauthenticated path traversal issue"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-54617 (GCVE-0-2026-54617)

FKIE_CVE-2026-54617

GHSA-5G75-477J-2C2F

Summary

Details

PoC

Impact

Suggested fix

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