CVE-2026-1810: Bolo-Solo Path Traversal Vulnerability

CVE-2026-1810 Overview

A path traversal vulnerability has been discovered in bolo-blog bolo-solo versions up to 2.6.4. The vulnerability exists in the unpackFilteredZip function within the BackupService.java file, which is part of the ZIP File Handler component. By manipulating the File argument, an attacker can traverse directory paths and potentially access or overwrite files outside the intended directory structure. This vulnerability can be exploited remotely by authenticated users.

Critical Impact

Remote attackers with low privileges can exploit this path traversal vulnerability to read or write files outside the intended directory, potentially leading to unauthorized data access, configuration tampering, or code execution through file overwrites.

Affected Products

• bolo-blog bolo-solo versions up to 2.6.4
• ZIP File Handler component in src/main/java/org/b3log/solo/bolo/prop/BackupService.java

Discovery Timeline

• 2026-02-03 - CVE-2026-1810 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-1810

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as Path Traversal or Directory Traversal. The flaw resides in the unpackFilteredZip function within the BackupService.java file, which handles ZIP file extraction operations for the backup functionality.

When processing ZIP archives, the application fails to properly sanitize or validate file paths contained within the archive entries. This allows an attacker to craft a malicious ZIP file containing entries with path traversal sequences (such as ../) that, when extracted, write files to arbitrary locations outside the intended extraction directory.

The vulnerability requires low-level authentication to exploit, meaning an attacker needs valid credentials to access the backup functionality. However, once authenticated, the attack can be carried out remotely over the network with low complexity, as no special conditions or user interaction are required beyond submitting the malicious ZIP file.

Root Cause

The root cause of this vulnerability is insufficient input validation in the unpackFilteredZip function. The code does not properly verify that extracted file paths remain within the designated extraction directory. When a ZIP entry contains relative path components like ../, the function processes these without sanitization, allowing the extraction process to write files to parent directories or other arbitrary locations on the file system.

Attack Vector

The attack can be executed remotely over the network by an authenticated user. The attacker crafts a malicious ZIP file containing entries with manipulated file paths that include directory traversal sequences. When this ZIP file is processed by the backup restoration or import functionality in bolo-solo, the vulnerable unpackFilteredZip function extracts the files to unintended locations.

The exploit has been publicly disclosed through GitHub Issue #326, and the project maintainers have been notified but have not yet responded. Additional technical details are available in the VulDB threat report.

Detection Methods for CVE-2026-1810

Indicators of Compromise

• Unexpected files appearing outside the application's backup directory structure
• ZIP file uploads containing entries with ../ path sequences in filenames
• Unauthorized modifications to configuration files or web application files
• Log entries showing backup restoration or import operations followed by suspicious file access

Detection Strategies

• Monitor file system operations for writes outside the expected backup extraction directories
• Implement web application firewall (WAF) rules to inspect uploaded ZIP files for path traversal sequences
• Review application logs for backup/restore operations that coincide with unauthorized file modifications
• Deploy file integrity monitoring on critical application directories and configuration files

Monitoring Recommendations

• Enable verbose logging for the BackupService component to capture all file extraction operations
• Set up alerts for any file creation or modification events outside the application's designated directories
• Monitor for unusual patterns in backup-related API endpoints or file upload functionality
• Implement real-time file integrity monitoring using SentinelOne Singularity to detect unauthorized file changes

How to Mitigate CVE-2026-1810

Immediate Actions Required

• Restrict access to backup and restore functionality to only trusted administrators
• Implement additional authentication requirements for backup-related operations
• Consider disabling the backup import functionality until a patch is available
• Review file system permissions to limit the application's write access to only necessary directories

Patch Information

At the time of publication, no official patch has been released by the bolo-solo project maintainers. The vulnerability was reported through GitHub Issue #326, but the project has not yet responded. Users should monitor the bolo-solo GitHub repository for updates and apply any security patches as soon as they become available.

Workarounds

• Implement input validation at the application layer to reject ZIP entries containing path traversal sequences
• Use a reverse proxy or WAF to inspect and filter uploaded ZIP files before they reach the application
• Run the application with minimal file system permissions using a dedicated service account
• Deploy the application in a containerized environment with restricted mount points to limit the impact of path traversal

The following configuration demonstrates how to implement path validation when extracting ZIP files to prevent traversal attacks:

// Secure ZIP extraction pattern
// Validate that resolved path stays within target directory
File targetDir = new File("/app/backups");
String canonicalTargetPath = targetDir.getCanonicalPath();

// For each ZIP entry, verify path before extraction
File extractedFile = new File(targetDir, zipEntry.getName());
String canonicalExtractedPath = extractedFile.getCanonicalPath();

if (!canonicalExtractedPath.startsWith(canonicalTargetPath + File.separator)) {
    throw new SecurityException("Path traversal attempt detected: " + zipEntry.getName());
}