CVE-2026-0992
📋 TL;DR
This vulnerability in libxml2 allows remote attackers to cause denial-of-service by sending crafted XML catalogs with repeated <nextCatalog> elements pointing to the same downstream catalog. This causes excessive CPU consumption through redundant catalog chain traversal, degrading application availability. Any application using vulnerable libxml2 versions to parse XML catalogs is affected.
💻 Affected Systems
- libxml2
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to CPU exhaustion, potentially affecting multiple applications sharing the same libxml2 library.
Likely Case
Degraded performance and intermittent service disruptions when processing malicious XML catalogs.
If Mitigated
Minimal impact with proper input validation and resource limits in place.
🎯 Exploit Status
Exploitation requires ability to supply XML catalogs to vulnerable applications. No authentication needed if application accepts external XML catalogs.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor-specific releases (e.g., Red Hat, Ubuntu, etc.)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2026-0992
Restart Required: Yes
Instructions:
1. Check your distribution's security advisories. 2. Update libxml2 package using your package manager. 3. Restart affected applications using libxml2. 4. Verify the update was successful.
🔧 Temporary Workarounds
Disable XML catalog processing
allIf XML catalog functionality is not required, disable it in application configuration.
Application-specific configuration changes required
Implement XML input validation
allValidate and sanitize XML input before processing, rejecting catalogs with repeated <nextCatalog> elements.
Implement custom XML validation logic in applications
🧯 If You Can't Patch
- Implement network segmentation to limit access to XML processing services
- Deploy rate limiting and CPU usage monitoring for XML processing applications
🔍 How to Verify
Check if Vulnerable:
Check libxml2 version: xml2-config --version or rpm -q libxml2Check Version:
xml2-config --version || rpm -q libxml2 || dpkg -l libxml2Verify Fix Applied:
Verify updated version matches vendor's patched version and test with sample XML catalogs.📡 Detection & Monitoring
Log Indicators:
- High CPU usage by processes using libxml2
- XML parsing errors or timeouts
Network Indicators:
- Unusual volume of XML traffic to applications
- Repeated XML catalog requests
SIEM Query:
process.name:libxml AND cpu.usage > 90% OR xml.parse.error