CVE-2026-26345
📋 TL;DR
This CVE describes a cross-site scripting (XSS) vulnerability in SPIP CMS versions before 4.4.8. The echapper_html_suspect() function fails to properly sanitize certain edge-case inputs, allowing attackers to inject malicious scripts that execute in visitors' browsers. This affects all SPIP installations with public-facing content areas.
💻 Affected Systems
- SPIP CMS
📦 What is this software?
Spip by Spip
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal session cookies, redirect users to malicious sites, deface websites, or perform actions on behalf of authenticated users.
Likely Case
Attackers inject malicious scripts to steal user session data or credentials from visitors accessing compromised pages.
If Mitigated
With proper input validation and output encoding, the risk is reduced to minimal, though the underlying vulnerability remains.
🎯 Exploit Status
XSS vulnerabilities typically have low exploitation complexity once the specific edge-case is identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.4.8
Vendor Advisory: https://blog.spip.net/Mise-a-jour-de-securite-sortie-de-SPIP-4-4-8.html
Restart Required: No
Instructions:
1. Backup your SPIP installation and database. 2. Download SPIP 4.4.8 from the official repository. 3. Replace the existing installation files with the updated version. 4. Clear any caches if applicable.
🔧 Temporary Workarounds
Input Validation Filter
allImplement additional input validation for user-submitted content in public areas
Content Security Policy
allImplement strict CSP headers to mitigate XSS impact
Header set Content-Security-Policy "default-src 'self'; script-src 'self'"
Header set X-Content-Type-Options "nosniff"
🧯 If You Can't Patch
- Implement a Web Application Firewall (WAF) with XSS protection rules
- Disable or restrict user content submission in public areas
🔍 How to Verify
Check if Vulnerable:
Check SPIP version in administration panel or by examining the spip_version.php fileCheck Version:
grep -r "define.*_SPIP_VERSION" /path/to/spip/installation/ | head -1Verify Fix Applied:
Confirm version is 4.4.8 or later in administration panel📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to content submission endpoints
- Requests containing suspicious script tags or JavaScript patterns
Network Indicators:
- Incoming requests with encoded script payloads in parameters
SIEM Query:
source="web_logs" AND (url="*spip.php*" OR url="*public/*") AND (message="*<script*" OR message="*javascript:*")