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Technical Analysis: Gogs Path Traversal (CVE-2025-8110)

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The cybersecurity landscape in 2026 has been punctuated by the return of classic vulnerabilities in modern clothing. One of the most significant examples is CVE-2025-8110, a critical path traversal vulnerability in Gogs, a popular self-hosted Git service. This flaw has sent shockwaves through the DevSecOps community, not just because of its severity, but because it represents a complete bypass of a previous security fix (CVE-2024-55947).

As organizations increasingly rely on self-hosted infrastructure to maintain data sovereignty, vulnerabilities like CVE-2025-8110 highlight the “blind spots” that occur when complex file system behaviors, such as symbolic links, are not properly sanitized. With over 700 instances already reported as compromised by automated malware like Supershell, understanding the technical mechanics of this exploit is mandatory for any security-conscious team.

1. The Critical Anatomy of CVE-2025-8110

At its core, CVE-2025-8110 is a failure of input validation. While the Gogs maintainers had previously implemented checks to prevent “dot-dot-slash” (../) style path traversal, they failed to account for how the underlying operating system handles symbolic links (symlinks) within the Git repository structure.

The Evolution from CVE-2024-55947

In late 2024, Gogs patched a vulnerability that allowed attackers to write files outside the repository using standard path traversal characters. The fix involved sanitizing the path parameter in the API. However, CVE-2025-8110 proves that sanitizing the string isn’t enough if the destination of that path is a malicious link.

How the Symlink Bypass Works

  1. Trusting Git Metadata: Gogs, by design, allows users to commit symbolic links to a repository.
  2. The PutContents API: This specific API is used to update file contents via the web interface.
  3. The Logical Gap: When a user calls PutContents to update a file named config, Gogs checks if config contains restricted characters. If it passes, Gogs writes the data.
  4. The Exploit: If config is actually a symlink pointing to /etc/passwd or .git/config on the host, the operating system follows the link, allowing the attacker to overwrite a file outside the intended sandbox.

2. Technical Breakdown: Achieving Remote Code Execution (RCE)

A path traversal flaw that allows arbitrary file writes is dangerous, but in Gogs, it leads directly to a full system compromise. The most common attack vector involves overwriting the internal Git configuration.

Overwriting .git/config

The ultimate goal for an attacker exploiting CVE-2025-8110 is usually the sshCommand field within a repository’s .git/config file. By using the path traversal to overwrite this file, an attacker can inject a malicious command that executes every time a Git operation (like a push or pull) is performed.

The Attack Chain:

3. Mandatory Remediation: How to Patch and Secure Gogs

If you are running Gogs version 0.13.3 or earlier, your instance is likely vulnerable and may already be compromised.

Step 1: Upgrade to Gogs 0.13.4+

The primary fix involves upgrading to the latest version where the maintainers have moved toward a more robust validation approach. The patch (Pull Request #8071) specifically addresses symlink handling in the API routes to ensure that file writes cannot cross-reference targets outside the repository root.

Step 2: Disable Open Registration

The most effective immediate mitigation, even before patching, is to set ENABLE_REGISTRATION = false in your app.ini. Since the exploit requires an authenticated user to create a repository, closing public registration cuts off the attacker’s primary entry point.

Step 3: Audit for Indicators of Compromise (IoC)

Automated scanners are currently targeting Gogs instances to deploy the “Supershell” malware. Look for the following signs:

4. Why Path Traversal Remains a Top Threat in 2026

CVE-2025-8110 is a reminder that as we add layers of abstraction (like Git APIs) on top of traditional file systems, the complexity of security increases exponentially. “Dot-dot-slash” might be a solved problem, but symlink races and bypasses are the new frontier for attackers.

The Role of Automated Exploitation

We are seeing a trend where vulnerabilities like this are exploited within hours of discovery. Threat actors use massive botnets to scan the entire IPv4 space, specifically looking for the Gogs signature. This “Time-to-Exploit” window has shrunk so significantly that manual patching is often too late.

5. Conclusion: Lessons for Developers

To prevent vulnerabilities like CVE-2025-8110, developers must adopt a “Secure by Default” mindset. This includes using “Chroot” or containerization to physically isolate the file system, and always resolving absolute paths before performing any write operation.

Protecting your infrastructure in 2026 requires constant vigilance. By understanding the mechanics of path traversal and symlink abuse, you can build a more resilient defense against the next wave of critical CVEs.

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