CVE-2026-15343
Summary
by MITRE • 07/17/2026
A path traversal vulnerability was identified in GitHub Enterprise Server that allowed an attacker who had code execution inside the Dependabot updater container to write files to arbitrary repository paths, including GitHub Actions workflow files under .github/workflows/ as the path validation did not check the effective path which the attacker could control through the dependency file's directory and symlink target. If the repository used a pull_request_target workflow or had auto-merge enabled, an injected workflow could execute with access to the repository's GitHub Actions secrets. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.3, 3.20.5, 3.19.9, 3.18.12, 3.17.18.
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Analysis
by VulDB Data Team • 07/17/2026
This vulnerability represents a critical path traversal flaw in GitHub Enterprise Server that demonstrates how seemingly isolated container execution environments can be exploited to achieve arbitrary file write capabilities within repository structures. The issue specifically targeted the Dependabot updater container functionality where attackers with code execution privileges could manipulate file paths through symbolic link manipulation and dependency directory traversal. The root cause lies in inadequate path validation mechanisms that failed to properly sanitize or verify the effective paths that attackers could control through the dependency file's directory structure and symlink targets.
The technical implementation of this vulnerability exploits the fundamental weakness in path resolution where the system accepted attacker-controlled paths without proper canonicalization checks. When Dependabot processed dependency files, it would traverse symbolic links and directory structures that allowed an attacker to manipulate the final write destination. This flaw specifically enabled attackers to target sensitive repository locations including the .github/workflows/ directory where GitHub Actions workflow files are stored. The vulnerability's severity increases significantly because it allows for the injection of malicious workflows that can execute with elevated privileges, particularly when repositories utilize pull_request_target triggers or auto-merge features.
The operational impact of this vulnerability extends beyond simple file manipulation to potential privilege escalation and secret exposure within affected repositories. When attackers successfully injected workflow files into the .github/workflows/ directory, these malicious workflows could execute with access to repository secrets, including deployment credentials, API tokens, and other sensitive information stored in GitHub Actions environments. The combination of pull_request_target workflows and auto-merge functionality creates a particularly dangerous scenario where injected workflows could automatically execute without manual intervention, potentially leading to complete repository compromise and unauthorized access to connected systems.
This vulnerability aligns with CWE-22 Path Traversal and CWE-73 Improper Neutralization of Special Elements in Output Used by a Downstream Component, demonstrating how insufficient input validation can lead to severe downstream consequences. The ATT&CK framework categorizes this as T1059 Command and Scripting Interpreter and T1566 Phishing, as the attack chain typically begins with code execution within the container environment followed by privilege escalation through workflow injection. Organizations using GitHub Enterprise Server prior to version 3.22 faced significant risk exposure, particularly those implementing automated CI/CD pipelines with repository secrets or sensitive deployment configurations.
The remediation approach required immediate patching across multiple version lines including 3.21.3, 3.20.5, 3.19.9, 3.18.12, and 3.17.18 to address the path traversal vulnerability in Dependabot container operations. System administrators should implement comprehensive monitoring for unauthorized workflow file modifications and review repository access controls to minimize potential attack surface. The fix required strengthening path validation logic to properly canonicalize and validate all paths before file operations, ensuring that symbolic links and directory traversals are properly sanitized to prevent effective path manipulation by attackers.