CVE-2022-0415: Gogs Repository File Upload RCE Vulnerability

CVE-2022-0415 Overview

CVE-2022-0415 is a Remote Command Execution (RCE) vulnerability in Gogs, a popular self-hosted Git service. The vulnerability exists in the repository file upload functionality, where insufficient validation of the upload TreePath and file name parameters allows authenticated attackers to execute arbitrary commands on the server. Gogs versions prior to 0.12.6 are affected by this security flaw.

Critical Impact
Authenticated attackers can achieve remote command execution on servers running vulnerable Gogs instances, potentially leading to complete system compromise, data exfiltration, and lateral movement within the network.

Affected Products

Gogs versions prior to 0.12.6
Self-hosted Gogs installations with file upload functionality enabled
Any deployment using unpatched gogs:gogs components

Discovery Timeline

2022-03-21 - CVE-2022-0415 published to NVD
2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-0415

Vulnerability Analysis

This vulnerability stems from improper input validation (CWE-20) and unrestricted file upload capabilities (CWE-434) in the Gogs repository editor module. The application fails to properly sanitize the TreePath parameter and file names during the repository file upload process, allowing attackers to bypass security controls and execute arbitrary commands.

The attack can be performed remotely over the network by any authenticated user with repository access. No user interaction is required beyond the initial authentication, and successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause lies in the internal/db/repo_editor.go file where the upload TreePath and file name parameters are not properly validated before being processed. The absence of path traversal checks and file type restrictions enables attackers to upload malicious files to arbitrary locations or craft specially formatted paths that result in command execution.

Attack Vector

The vulnerability is exploitable over the network by authenticated users. An attacker with valid credentials can:

Authenticate to the Gogs instance with any repository access
Navigate to the file upload functionality within a repository
Craft a malicious TreePath or file name parameter
Upload a file that triggers command execution on the server

The security patch introduced in commit 0fef3c9082269e9a4e817274942a5d7c50617284 addresses this by implementing proper path validation using the pathutil package:

 	"strings"
 	"time"
 
+	"github.com/pkg/errors"
 	gouuid "github.com/satori/go.uuid"
 	"github.com/unknwon/com"
 
 	"github.com/gogs/git-module"
 
 	"gogs.io/gogs/internal/conf"
 	"gogs.io/gogs/internal/cryptoutil"
-	"gogs.io/gogs/internal/db/errors"
+	dberrors "gogs.io/gogs/internal/db/errors"
 	"gogs.io/gogs/internal/gitutil"
 	"gogs.io/gogs/internal/osutil"
+	"gogs.io/gogs/internal/pathutil"
 	"gogs.io/gogs/internal/process"
 	"gogs.io/gogs/internal/tool"
)

Source: GitHub Commit Details

Detection Methods for CVE-2022-0415

Indicators of Compromise

Unusual file upload requests to Gogs repositories with suspicious TreePath parameters containing path traversal sequences (e.g., ../, ..%2f)
Unexpected files appearing in system directories outside the repository structure
Abnormal process execution spawned by the Gogs service process
Web server logs showing malformed upload requests with encoded special characters

Detection Strategies

Monitor Gogs application logs for file upload operations with unusual path patterns or encoded characters
Implement web application firewall (WAF) rules to detect path traversal attempts in upload parameters
Deploy endpoint detection and response (EDR) solutions to identify command execution from Gogs processes
Review audit logs for authenticated users performing suspicious upload activities

Monitoring Recommendations

Enable verbose logging for the Gogs application to capture all file upload operations
Configure alerting on process creation events originating from the Gogs service account
Monitor network traffic for outbound connections initiated by the Gogs server that could indicate post-exploitation activity
Implement file integrity monitoring on critical system directories

How to Mitigate CVE-2022-0415

Immediate Actions Required

Upgrade Gogs to version 0.12.6 or later immediately
Review Gogs access logs for signs of exploitation attempts
Audit user accounts with repository access for any unauthorized activity
Consider temporarily disabling file upload functionality if immediate patching is not possible

Patch Information

The vulnerability has been addressed in Gogs version 0.12.6. The security fix was implemented in commit 0fef3c9082269e9a4e817274942a5d7c50617284, which adds proper validation of the upload TreePath and file name parameters using the pathutil package. Organizations should update to this version or later to remediate the vulnerability. For detailed patch information, refer to the GitHub Commit Details and the Huntr Bounty Report.

Workarounds

Restrict repository file upload permissions to only trusted administrators until the patch can be applied
Implement network segmentation to limit the blast radius if the Gogs server is compromised
Deploy a reverse proxy with strict input validation rules to filter malicious upload requests
Consider running Gogs in a containerized environment with restricted capabilities to limit post-exploitation impact

bash

# Example: Restrict file upload permissions via Gogs configuration
# Edit app.ini to limit upload capabilities
[repository.upload]
ENABLED = false  # Disable file uploads until patched
# Or restrict to specific file types
ALLOWED_TYPES = .md,.txt,.json