Comprehensive Technical Analysis of CVE-2026-25160

CVE ID: CVE-2026-25160 CVSS Score: 9.1 (Critical) Affected Software: Alist (prior to version 3.57.0) Vulnerability Type: Insecure Transport Security (TLS Certificate Verification Bypass)

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1. Vulnerability Assessment and Severity Evaluation

Vulnerability Overview

CVE-2026-25160 is a critical security misconfiguration in Alist, a file list program that supports multiple storage backends. The vulnerability stems from the application disabling TLS certificate verification by default for all outgoing storage driver communications. This flaw allows attackers to perform Man-in-the-Middle (MitM) attacks, leading to:

• Decryption of encrypted traffic (if TLS is used but improperly verified).
• Data exfiltration (theft of sensitive files, credentials, or metadata).
• Data tampering (modification of files in transit).
• Session hijacking (if authentication tokens are intercepted).

CVSS 9.1 (Critical) Breakdown

Metric	Value	Explanation
Attack Vector (AV)	Network (N)	Exploitable remotely over the network.
Attack Complexity (AC)	Low (L)	No special conditions required; standard MitM techniques apply.
Privileges Required (PR)	None (N)	No authentication or elevated privileges needed.
User Interaction (UI)	None (N)	Exploitation does not require user action.
Scope (S)	Unchanged (U)	Impact is confined to the vulnerable component (Alist).
Confidentiality (C)	High (H)	Full decryption of sensitive data in transit.
Integrity (I)	High (H)	Data can be modified in transit.
Availability (A)	None (N)	No direct impact on system availability.

Justification for Critical Severity:

• High Confidentiality & Integrity Impact: Unverified TLS allows attackers to intercept and manipulate all storage-related communications.
• Low Attack Complexity: MitM attacks are well-documented and can be executed with tools like Wireshark, mitmproxy, or Bettercap.
• No Privileges Required: Exploitation does not depend on compromised credentials or insider access.

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2. Potential Attack Vectors and Exploitation Methods

Attack Scenarios

A. Passive MitM (Eavesdropping)

1. Attacker Positioning:

   • The attacker must be on the same network segment as the victim (e.g., same LAN, public Wi-Fi, or compromised router).
   • Alternatively, the attacker could compromise an intermediate network device (e.g., ISP, CDN, or proxy).

2. Exploitation Steps:

   • ARP Spoofing / DNS Spoofing: Redirect victim traffic through the attacker’s machine.
   • TLS Downgrade (if applicable): If Alist attempts TLS but does not verify certificates, the attacker can intercept traffic without triggering warnings.
   • Decryption & Data Theft: All storage operations (uploads, downloads, metadata queries) are decrypted and logged.

3. Tools Used:

   • Wireshark (for packet capture).
   • mitmproxy (for intercepting and modifying TLS traffic).
   • Bettercap (for ARP/DNS spoofing).

B. Active MitM (Data Tampering)

1. Attacker Modifies Data in Transit:

   • If Alist retrieves a file from a storage backend (e.g., S3, FTP, WebDAV), the attacker can:
     • Replace legitimate files with malicious payloads (e.g., malware, ransomware).
     • Inject malicious scripts (e.g., XSS payloads in HTML files).
     • Alter metadata (e.g., file permissions, timestamps).

2. Impact:

   • Supply Chain Attacks: If Alist is used to distribute software, attackers could replace binaries with trojanized versions.
   • Credential Theft: If storage backends require authentication, intercepted credentials could be reused elsewhere.

C. Session Hijacking (If Applicable)

• If Alist uses session tokens (e.g., JWT, OAuth) for storage backend authentication, an attacker could:
  • Steal tokens and impersonate the victim.
  • Replay requests to exfiltrate additional data.

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3. Affected Systems and Software Versions

Vulnerable Versions

• All versions of Alist prior to 3.57.0 are affected.
• The vulnerability is independent of the storage backend (e.g., S3, FTP, WebDAV, Google Drive) since it pertains to outgoing TLS verification.

Non-Vulnerable Versions

• Alist v3.57.0 and later (patched version).
• The fix enforces TLS certificate validation by default.

Deployment Scenarios at Risk

Scenario	Risk Level	Explanation
Self-hosted Alist (LAN/WAN)	Critical	Attackers on the same network can exploit MitM.
Cloud-hosted Alist (Public Internet)	Critical	Attackers can intercept traffic via compromised ISPs, CDNs, or proxies.
Alist behind a reverse proxy (e.g., Nginx, Cloudflare)	High	If the proxy does not enforce TLS validation, MitM is still possible.
Alist with custom storage backends (e.g., S3, FTP)	Critical	All storage operations are vulnerable.

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4. Recommended Mitigation Strategies

Immediate Actions

1. Upgrade to Alist v3.57.0 or Later

   • The patch enforces TLS certificate validation by default.
   • Verification Steps:
     • Check the commit: 69629ca76a8f2c8c973ede3b616f93aa26ff23fb.
     • Ensure tls.Config.InsecureSkipVerify = false is set in the codebase.

2. Enforce TLS Validation in Custom Configurations

   • If upgrading is not immediately possible, manually enforce TLS verification in storage driver configurations.
   • Example (Go code snippet):

     import (
         "crypto/tls"
         "net/http"
     )
     
     tr := &http.Transport{
         TLSClientConfig: &tls.Config{InsecureSkipVerify: false}, // Force validation
     }
     client := &http.Client{Transport: tr}
     

3. Network-Level Protections

   • Use VPNs or Zero Trust Network Access (ZTNA) to prevent MitM on untrusted networks.
   • Deploy Mutual TLS (mTLS) for storage backend communications.
   • Monitor for ARP/DNS spoofing using tools like Arpwatch or Zeek (Bro).

4. Storage Backend Hardening

   • Enable TLS 1.2+ on all storage backends (disable SSLv3, TLS 1.0/1.1).
   • Use certificate pinning (HPKP) for critical storage endpoints.
   • Rotate storage credentials if MitM exposure is suspected.

Long-Term Recommendations

1. Security Audits & Code Reviews

   • Conduct a full TLS configuration audit to ensure no other components disable certificate validation.
   • Implement automated security testing (e.g., OWASP ZAP, Burp Suite) to detect similar misconfigurations.

2. Incident Response Planning

   • Assume breach: If Alist was exposed, rotate all storage credentials and audit logs for unauthorized access.
   • Deploy network segmentation to limit lateral movement in case of exploitation.

3. User Awareness & Training

   • Educate administrators on TLS best practices and MitM risks.
   • Encourage the use of hardened storage backends (e.g., AWS S3 with VPC endpoints, SFTP with key-based auth).

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5. Impact on the Cybersecurity Landscape

Broader Implications

1. Supply Chain Risks

   • Alist is often used as a file distribution tool in DevOps pipelines. A MitM attack could lead to malicious software updates being distributed to end users.
   • Example: If a company uses Alist to host internal binaries, attackers could replace them with backdoored versions.

2. Compliance Violations

   • GDPR, HIPAA, PCI DSS require secure data transmission. Unverified TLS violates these standards, leading to legal and financial penalties.
   • NIST SP 800-52 explicitly mandates TLS certificate validation.

3. Increased MitM Attack Surface

   • This vulnerability highlights a common misconfiguration in Go-based applications (Gin framework).
   • Similar flaws have been found in Docker, Kubernetes, and other cloud-native tools, indicating a systemic issue in TLS implementation.

4. Threat Actor Exploitation

   • APT Groups & Cybercriminals may exploit this in:
     • Espionage campaigns (stealing sensitive documents).
     • Ransomware attacks (modifying files before encryption).
     • Credential harvesting (intercepting storage backend logins).

Comparison to Known Vulnerabilities

Vulnerability	Similarity	Key Difference
CVE-2021-44228 (Log4Shell)	Remote exploitation	Log4Shell was RCE; this is MitM.
CVE-2014-0160 (Heartbleed)	TLS-related	Heartbleed leaked memory; this bypasses validation.
CVE-2016-2107 (OpenSSL Padding Oracle)	MitM risk	This is a misconfiguration, not a crypto flaw.

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6. Technical Details for Security Professionals

Root Cause Analysis

• Code-Level Issue:

  • Alist’s storage drivers (e.g., S3, FTP) used http.Client with InsecureSkipVerify: true, disabling TLS certificate validation.
  • Example (Vulnerable Code):

    tr := &http.Transport{
        TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, // Bypasses validation
    }
    client := &http.Client{Transport: tr}
    

  • Fixed Code (v3.57.0):

    tr := &http.Transport{
        TLSClientConfig: &tls.Config{InsecureSkipVerify: false}, // Enforces validation
    }
    

• Why This Happened:

  • Developer Convenience: Disabling TLS verification simplifies testing with self-signed certificates.
  • Lack of Security Review: No automated checks for insecure TLS configurations.
  • Framework Defaults: Some Go libraries (e.g., Gin) do not enforce secure defaults.

Exploitation Proof of Concept (PoC)

1. Setup:

   • Attacker and victim on the same network.
   • Alist configured to use an S3 bucket (or any storage backend).

2. Steps:

   • ARP Spoofing (Bettercap):

     bettercap -iface eth0 -caplet hstshijack/hstshijack
     

   • Intercept TLS Traffic (mitmproxy):

     mitmproxy --mode transparent --showhost
     

   • Trigger Alist Storage Operation:
     • Victim uploads/downloads a file via Alist.
   • Observe Decrypted Traffic:
     • mitmproxy displays plaintext HTTP requests (if TLS is downgraded) or decrypted TLS traffic (if validation is bypassed).

3. Expected Output:

   • Attacker sees file contents, credentials, and metadata in plaintext.

Detection & Forensics

1. Network-Level Detection:

   • Zeek (Bro) Script to Detect Unverified TLS:

     event ssl_established(c: connection, version: count, cipher: count) {
         if (c$ssl?$validation_status && c$ssl$validation_status == "unverified") {
             NOTICE([$note=SSL::Unverified_Certificate,
                     $msg=fmt("Unverified TLS connection to %s", c$id$resp_h),
                     $conn=c]);
         }
     }
     

   • Wireshark Filter:

     tls.handshake.type == 11 && tls.handshake.certificate_request == 0
     

2. Log Analysis:

   • Check Alist logs for storage operations and correlate with unusual network activity.
   • Look for unexpected TLS handshake failures (indicating MitM attempts).

3. Endpoint Detection:

   • YARA Rule for Alist Binary Analysis:

     rule Alist_InsecureTLS {
         meta:
             description = "Detects Alist versions with InsecureSkipVerify=true"
             reference = "CVE-2026-25160"
         strings:
             $insecure_tls = "InsecureSkipVerify: true"
         condition:
             $insecure_tls
     }
     

Hardening Recommendations for Developers

1. Secure Defaults in Go:

   • Always set InsecureSkipVerify: false unless explicitly required (e.g., internal testing).
   • Use crypto/tls with strict validation:

     tlsConfig := &tls.Config{
         MinVersion:               tls.VersionTLS12,
         CurvePreferences:         []tls.CurveID{tls.CurveP521, tls.CurveP384, tls.CurveP256},
         PreferServerCipherSuites: true,
         CipherSuites: []uint16{
             tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
             tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
         },
     }
     

2. Automated Security Testing:

   • Integrate static analysis tools (e.g., Gosec, Semgrep) to detect InsecureSkipVerify.
   • Example Gosec rule:

     rules:
       - id: G402
         pattern: tls.Config{InsecureSkipVerify: true}
         message: "TLS certificate validation is disabled (CWE-295)"
     

3. Runtime Protection:

   • Use eBPF-based monitoring (e.g., Falco, Tetragon) to detect MitM attempts.
   • Deploy TLS inspection proxies (e.g., Squid, HAProxy) to enforce validation.

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Conclusion

CVE-2026-25160 is a critical security misconfiguration that exposes Alist users to MitM attacks, leading to data theft, tampering, and session hijacking. The vulnerability is easily exploitable with low complexity and has severe confidentiality and integrity impacts.

Immediate action is required:

1. Upgrade to Alist v3.57.0+ to enforce TLS validation.
2. Audit all TLS configurations in custom deployments.
3. Monitor for MitM attacks using network detection tools.

This vulnerability underscores the importance of secure defaults in software development and the need for rigorous TLS validation in all network communications. Organizations using Alist should assume compromise if running unpatched versions and take proactive forensic measures to detect exploitation.