EUVD-2026-5367: Comprehensive Technical Analysis

Executive Summary

EUVD-2026-5367 (CVE-2026-25160) represents a critical security vulnerability in Alist, a multi-storage file list program. The vulnerability stems from disabled TLS certificate verification in storage driver communications, creating a systemic exposure to Man-in-the-Middle (MitM) attacks. With a CVSS v3.1 score of 9.1 (Critical), this vulnerability poses severe risks to data confidentiality and integrity across all affected deployments.

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1. Vulnerability Assessment and Severity Evaluation

Technical Classification

• Vulnerability Type: Improper Certificate Validation (CWE-295)
• CVSS v3.1 Score: 9.1 (Critical)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)

Severity Justification

The 9.1 CVSS score is warranted due to:

High Confidentiality Impact (C:H):

• Complete exposure of data in transit to storage backends
• Potential credential theft for storage systems
• Exposure of sensitive file contents and metadata

High Integrity Impact (I:H):

• Attackers can modify data streams without detection
• File corruption or malicious payload injection possible
• Storage operations can be manipulated silently

No Availability Impact (A:N):

• The vulnerability doesn't directly cause service disruption
• However, secondary impacts (data corruption) could affect availability

Network Attack Vector (AV:N):

• Exploitable remotely by any network-positioned attacker
• No physical or local access required

Risk Assessment

This vulnerability is particularly severe because:

1. Default Configuration Flaw: The insecure setting is enabled by default, affecting all unpatched installations
2. Silent Exploitation: MitM attacks leave minimal forensic evidence
3. Broad Attack Surface: Affects all storage driver communications
4. No Authentication Required: Attackers need only network positioning

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2. Potential Attack Vectors and Exploitation Methods

Primary Attack Scenarios

Scenario 1: Network-Level MitM Attack

User/Application → [Attacker Proxy] → Storage Backend
                    ↓
              Intercept & Decrypt
              Modify & Re-encrypt

Prerequisites:

• Network positioning between Alist instance and storage backend
• Achievable through:
  • Compromised network infrastructure
  • ARP spoofing on local networks
  • DNS hijacking
  • BGP hijacking for cloud-to-cloud communications
  • Compromised ISP or cloud provider infrastructure

Exploitation Steps:

1. Position attacker-controlled system in network path
2. Intercept TLS handshake between Alist and storage backend
3. Present fraudulent certificate to Alist
4. Alist accepts invalid certificate due to disabled verification
5. Establish separate TLS connection to legitimate storage backend
6. Decrypt, inspect, modify, and re-encrypt all traffic

Scenario 2: Cloud Environment Exploitation

• Multi-tenant Cloud Risks: Attackers with access to shared infrastructure can intercept traffic
• Compromised Cloud Credentials: Access to cloud networking allows traffic redirection
• Malicious Cloud Providers: Rogue or compromised cloud services can exploit this vulnerability

Scenario 3: Supply Chain Attack

• Compromise of DNS infrastructure to redirect storage endpoints
• Substitution of legitimate storage backends with malicious replicas
• Long-term data exfiltration without detection

Exploitation Complexity

Low Complexity Factors:

• No exploit code required; standard MitM tools suffice (mitmproxy, Burp Suite, custom proxies)
• No authentication bypass needed
• No timing or race conditions to exploit
• Reliable and repeatable exploitation

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3. Affected Systems and Software Versions

Directly Affected Software

• Product: Alist
• Vendor: AlistGo
• Affected Versions: All versions < 3.57.0
• Patched Version: 3.57.0 and later
• Technology Stack: Gin (Go framework) and SolidJS

Affected Storage Drivers

The vulnerability impacts all storage backend communications, potentially including:

• Cloud Storage: AWS S3, Azure Blob Storage, Google Cloud Storage
• WebDAV Servers
• FTP/SFTP Servers (if using TLS)
• OneDrive, Dropbox, and other cloud providers
• Self-hosted Storage Solutions
• Any storage backend requiring TLS communication

Deployment Scenarios at Risk

1. Enterprise File Management Systems

   • Organizations using Alist for centralized file access
   • Multi-cloud storage aggregation platforms

2. Personal Cloud Storage Aggregators

   • Individual users consolidating multiple storage accounts
   • Home lab and self-hosted environments

3. Service Providers

   • Hosting providers offering Alist as a service
   • Managed file storage platforms

4. Development and Testing Environments

   • CI/CD pipelines using Alist for artifact storage
   • Development teams with shared storage access

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4. Recommended Mitigation Strategies

Immediate Actions (Priority 1)

1. Upgrade to Patched Version

# Recommended immediate action
# Upgrade to Alist version 3.57.0 or later
docker pull xhofe/alist:v3.57.0
# or
wget https://github.com/AlistGo/alist/releases/download/v3.57.0/alist-linux-amd64.tar.gz

Verification:

• Review commit: 69629ca76a8f2c8c973ede3b616f93aa26ff23fb
• Confirm TLS certificate verification is enabled post-upgrade
• Test storage connectivity after upgrade

2. Network Segmentation

• Isolate Alist instances in trusted network segments
• Implement strict firewall rules limiting outbound connections
• Use VPN or private networking for storage backend communications

3. Immediate Risk Assessment

• Audit all Alist deployments in your environment
• Identify instances communicating with external storage
• Review logs for suspicious connection patterns (if available)

Short-Term Mitigations (Priority 2)

1. Network-Level TLS Inspection

• Deploy TLS-inspecting proxies with valid certificate chains
• Implement network-based certificate pinning where possible
• Monitor for certificate anomalies

2. Enhanced Monitoring

Key Indicators to Monitor:
- Unexpected certificate changes in storage connections
- Unusual data transfer patterns
- Connection attempts from unexpected IP addresses
- Storage authentication failures
- Latency increases (potential proxy insertion)

3. Access Control Hardening

• Implement principle of least privilege for Alist instances
• Restrict network access to known storage endpoints only
• Use IP whitelisting where supported by storage providers

Long-Term Strategic Measures (Priority 3)

1. Security Architecture Review

• Evaluate all applications for similar TLS validation issues
• Implement secure-by-default configuration policies
• Establish code review processes for TLS implementations

2. Certificate Management

• Deploy internal PKI for private storage backends
• Implement certificate pinning for known storage endpoints
• Regular certificate rotation and monitoring

3. Incident Response Preparation

Develop playbooks for:
- Detection of MitM attacks
- Forensic analysis of compromised data flows
- Data integrity verification procedures
- Credential rotation for potentially exposed storage accounts

4. Vendor Security Assessment

• Establish security requirements for third-party software
• Regular vulnerability scanning of deployed applications
• Participation in vendor security advisory programs

Compensating Controls (If Upgrade Not Immediately Possible)

1. Network Isolation: Deploy Alist only in fully trusted networks
2. VPN Tunneling: Force all storage traffic through authenticated VPN tunnels
3. Proxy with Certificate Validation: Route traffic through validating proxy
4. Disable External Storage: Temporarily disable untrusted storage backends

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5. Impact on European Cybersecurity Landscape

Regulatory Compliance Implications