CVE-2025-2866
📋 TL;DR
A cryptographic signature verification flaw in LibreOffice allows attackers to spoof PDF signatures by making invalid signatures appear valid. This affects users who rely on LibreOffice's PDF signature verification feature. The vulnerability impacts LibreOffice versions 24.8 to 24.8.5 and 25.2 to 25.2.1.
💻 Affected Systems
- LibreOffice
📦 What is this software?
Libreoffice by Libreoffice
Libreoffice by Libreoffice
Libreoffice by Libreoffice
Libreoffice by Libreoffice
Libreoffice by Libreoffice
Libreoffice by Libreoffice
⚠️ Risk & Real-World Impact
Worst Case
Attackers could forge digitally signed PDF documents that appear legitimate, potentially leading to acceptance of malicious contracts, fraudulent financial documents, or tampered legal agreements.
Likely Case
Users might accept PDF documents with spoofed signatures, compromising document integrity verification and potentially enabling social engineering attacks.
If Mitigated
With proper controls like verifying signatures through alternative methods and user awareness training, the impact is limited to potential confusion rather than actual harm.
🎯 Exploit Status
Exploitation requires crafting malicious PDF files with spoofed signatures. Attackers need to trick users into opening these files.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 24.8.6 or 25.2.2
Vendor Advisory: https://www.libreoffice.org/about-us/security/advisories/cve-2025-2866
Restart Required: Yes
Instructions:
1. Download LibreOffice 24.8.6 or 25.2.2 from official website. 2. Run installer. 3. Restart LibreOffice applications.
🔧 Temporary Workarounds
Disable PDF signature verification
allTemporarily disable LibreOffice's PDF signature verification feature until patched.
Use alternative PDF viewers
allUse alternative PDF software for signature verification until LibreOffice is patched.
🧯 If You Can't Patch
- Implement strict document verification procedures requiring multiple signature validation methods
- Train users to verify PDF signatures using dedicated cryptographic tools rather than relying solely on LibreOffice
🔍 How to Verify
Check if Vulnerable:
Check LibreOffice version via Help > About LibreOffice. If version is between 24.8-24.8.5 or 25.2-25.2.1, system is vulnerable.Check Version:
libreoffice --versionVerify Fix Applied:
After update, verify version is 24.8.6 or higher (for 24.8 branch) or 25.2.2 or higher (for 25.2 branch).📡 Detection & Monitoring
Log Indicators:
- Unusual PDF file processing errors
- Multiple failed signature verification attempts
Network Indicators:
- Downloads of PDF files from untrusted sources
SIEM Query:
source="libreoffice" AND (event="signature_verification" OR event="pdf_processing")