CVE-2024-23807
📋 TL;DR
This CVE describes a use-after-free vulnerability in Apache Xerces C++ XML parser versions 3.0.0 through 3.2.4. When processing external DTDs, the parser can access freed memory, potentially allowing remote code execution or denial of service. Any application using vulnerable Xerces C++ versions for XML parsing is affected.
💻 Affected Systems
- Apache Xerces C++ XML Parser
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full system compromise, allowing attackers to execute arbitrary code on the affected system.
Likely Case
Denial of service through application crashes or memory corruption leading to instability.
If Mitigated
Minimal impact if DTD processing is disabled or proper input validation prevents malicious XML.
🎯 Exploit Status
The vulnerability requires crafting malicious XML with external DTDs. Similar to CVE-2018-1311, which had known exploitation patterns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.2.5
Vendor Advisory: https://lists.apache.org/thread/c497tgn864tsbm8w0bo3f0d81s07zk9r
Restart Required: Yes
Instructions:
1. Download Xerces C++ 3.2.5 from Apache website. 2. Replace existing Xerces C++ library files with new version. 3. Recompile any applications using Xerces C++. 4. Restart affected services.
🔧 Temporary Workarounds
Disable DTD Processing via DOM
allConfigure XML parser to disable DTD processing entirely
Set feature 'http://apache.org/xml/features/disallow-doctype-decl' to true in parser configuration
Disable DTD Processing via SAX
linuxUse environment variable to disable DTD processing in SAX parsers
export XERCES_DISABLE_DTD=1
🧯 If You Can't Patch
- Implement strict input validation to reject XML containing external DTDs
- Deploy network filtering to block XML payloads with DTD references at perimeter
🔍 How to Verify
Check if Vulnerable:
Check Xerces C++ library version using 'strings libxerces-c.so | grep Xerces' or similar on binary filesCheck Version:
xerces-c-3.2 --version (if installed) or check library files directlyVerify Fix Applied:
Verify version is 3.2.5 or higher and test XML parsing with DTDs to ensure no crashes📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory access violations
- XML parsing errors related to DTD processing
Network Indicators:
- Unusual XML payloads containing external DTD references
- Multiple failed XML parsing attempts
SIEM Query:
source="application.log" AND ("segmentation fault" OR "access violation" OR "XML parse error")