CVE-2020-10977: GitLab Path Traversal Vulnerability

CVE-2020-10977 Overview

CVE-2020-10977 is a path traversal vulnerability affecting GitLab Enterprise Edition (EE) and Community Edition (CE) versions 8.5 through 12.9. The vulnerability exists in the issue moving functionality, allowing authenticated attackers to read arbitrary files from the GitLab server by exploiting improper path validation when transferring issues between projects.

Critical Impact

Authenticated attackers can leverage this path traversal flaw to read sensitive files from the GitLab server, potentially exposing configuration files, secrets, and other confidential data. This vulnerability has been documented with remote code execution possibilities when chained with other techniques.

Affected Products

• GitLab Community Edition versions 8.5 to 12.9
• GitLab Enterprise Edition versions 8.5 to 12.9

Discovery Timeline

• 2020-03-26 - GitLab releases security patch version 12.9.1
• 2020-04-08 - CVE-2020-10977 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-10977

Vulnerability Analysis

This path traversal vulnerability (CWE-22) exists within GitLab's issue management system, specifically in the functionality that allows users to move issues between different projects. The flaw stems from insufficient input validation when processing file paths during the issue migration process.

An authenticated attacker with the ability to create and move issues can craft malicious requests that include directory traversal sequences (such as ../) to escape the intended directory structure. This allows the attacker to access files outside of the expected scope, potentially reading sensitive system files, configuration data, or application secrets stored on the GitLab server.

The vulnerability has been documented in conjunction with remote code execution techniques, as referenced in the Packet Storm Security advisory, where arbitrary file read capabilities can potentially be chained with other attack vectors to achieve code execution on the target system.

Root Cause

The root cause of CVE-2020-10977 is improper input validation in the issue move functionality. When a user moves an issue from one project to another, GitLab fails to properly sanitize file path inputs, allowing directory traversal sequences to be processed. This lack of path canonicalization or validation enables attackers to reference files outside the intended directory boundaries.

Attack Vector

The attack requires an authenticated user with permissions to create issues and move them between projects. The attacker crafts a specially formatted request containing path traversal sequences (e.g., ../../../etc/passwd) within the issue move operation. When processed by GitLab, these sequences are not properly sanitized, allowing the server to read and potentially expose files from arbitrary locations on the file system.

The attack flow typically involves:

1. Attacker authenticates to the GitLab instance with valid credentials
2. Creates or identifies an issue in a project where they have write access
3. Initiates an issue move operation with crafted path traversal payloads
4. GitLab processes the malicious path without proper sanitization
5. Contents of the targeted file are exposed to the attacker

For detailed technical analysis and exploitation techniques, refer to the Packet Storm Security exploit documentation.

Detection Methods for CVE-2020-10977

Indicators of Compromise

• Unusual issue move operations containing path traversal patterns such as ../ or encoded variants (%2e%2e%2f)
• Web server logs showing requests with directory traversal sequences targeting the issue move API endpoints
• Unexpected file access attempts in system logs for sensitive files like /etc/passwd, configuration files, or secrets
• Anomalous user activity involving rapid creation and movement of issues across projects

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block requests containing path traversal patterns in issue-related API endpoints
• Monitor GitLab application logs for issue move operations with suspicious file path references
• Deploy file integrity monitoring on critical system and configuration files to detect unauthorized access attempts
• Enable detailed audit logging for issue management operations to track user activities

Monitoring Recommendations

• Configure alerting for any API requests to issue move endpoints containing traversal sequences or encoded path manipulation attempts
• Monitor for unusual patterns of issue creation and movement by single users, which may indicate exploitation attempts
• Implement network-level monitoring to detect outbound data exfiltration following potential file read operations
• Review GitLab access logs regularly for anomalous user behavior patterns

How to Mitigate CVE-2020-10977

Immediate Actions Required

• Upgrade GitLab CE/EE to version 12.9.1 or later immediately
• Review audit logs for any suspicious issue move operations that may have exploited this vulnerability
• Implement network segmentation to limit potential impact if exploitation has occurred
• Temporarily restrict issue move permissions to trusted users until patching is complete

Patch Information

GitLab has released a security update addressing this vulnerability. Users should upgrade to GitLab version 12.9.1 or later. The official security release announcement is available in the GitLab Security Release Notes.

Organizations running affected versions should prioritize this update, especially for internet-facing GitLab instances. The complete list of GitLab releases can be found at the GitLab Release Category page.

Workarounds

• If immediate patching is not possible, restrict the ability to move issues between projects by adjusting user permissions at the project or group level
• Implement additional input validation at the web application firewall level to block requests containing path traversal patterns
• Monitor and audit all issue move operations closely until the patch can be applied
• Consider temporarily disabling the issue move functionality if it is not critical to business operations

# Verify GitLab version after patching
gitlab-rake gitlab:env:info | grep "GitLab information"

# Check current GitLab version
cat /opt/gitlab/embedded/service/gitlab-rails/VERSION

# Review GitLab audit logs for suspicious activity
gitlab-rake gitlab:check SANITIZE=true