Gogs has arbitrary file read/write via Path Traversal in Git hook editing

Vulnerability Description

In the endpoint:

/username/reponame/settings/hooks/git/:name

the :name parameter:

• Is URL-decoded by macaron routing, allowing decoded slashes (/)
• Is then passed directly to:

git.Repository.Hook("custom_hooks", name)

which internally resolves the path as:

filepath.Join(repoPath, "custom_hooks", name)

Because no path sanitization is applied, supplying ../ sequences allows access to arbitrary paths outside the repository.

As a Result:

• GET: Arbitrary file contents are displayed in the hook edit page textarea (Local File Inclusion).
• POST: Existing files can be overwritten with attacker-controlled content (Arbitrary File Write).

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Attack Prerequisites

• The attacker is an authenticated user
• The attacker has Admin or higher privileges on the target repository
• The attacker has the AllowGitHook permission (or is a site administrator)
• The target file is readable/writable by the Gogs process OS permissions

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Attack Scenario

1. An attacker (with AllowGitHook + repository Admin privileges) accesses the Git hook edit URL
2. A path containing ../ is supplied in :name, fully URL-encoded using %2f
3. The server resolves custom_hooks/../../... without validation
4. Arbitrary file contents are displayed and existing files can be overwritten

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Potential Impact

• Sensitive information disclosure: app.ini, databases, logs, environment variables, etc.
• Configuration or data tampering: Overwriting existing files
• Secondary impact: Extraction of SECRET_KEY and database credentials may allow token forging or further compromise