CVE-2017-18926
📋 TL;DR
CVE-2017-18926 is a heap-based buffer overflow vulnerability in Raptor RDF Syntax Library's XML writer component. It allows attackers to execute arbitrary code or cause denial of service by triggering miscalculated memory allocations. Affects applications using vulnerable versions of the Raptor library for RDF processing.
💻 Affected Systems
- Raptor RDF Syntax Library
- Applications embedding Raptor library (e.g., Redland RDF libraries, some semantic web tools)
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.
Likely Case
Denial of service (application crash) or limited information disclosure through memory corruption.
If Mitigated
Application crash with no data loss if memory protections (ASLR, DEP) are effective.
🎯 Exploit Status
Proof-of-concept code exists in security advisories. Exploitation requires crafting specific RDF/XML input to trigger the buffer overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Raptor 2.0.16 and later
Vendor Advisory: http://www.librdf.org/
Restart Required: Yes
Instructions:
1. Identify applications using Raptor library. 2. Update to Raptor 2.0.16 or later. 3. Recompile applications if using embedded library. 4. Restart affected services.
🔧 Temporary Workarounds
Input validation and filtering
allImplement strict input validation for RDF/XML content before processing with Raptor library
Memory protection hardening
linuxEnable ASLR, DEP, and other memory protection mechanisms at OS and application level
echo 2 > /proc/sys/kernel/randomize_va_space
gcc -fPIE -pie -fstack-protector-all
🧯 If You Can't Patch
- Implement network filtering to block or inspect RDF/XML content to vulnerable endpoints
- Isolate affected systems in segmented network zones with strict access controls
🔍 How to Verify
Check if Vulnerable:
Check Raptor library version: raptor-config --version or ldd on binary to check linked library versionCheck Version:
raptor-config --version 2>/dev/null || find /usr -name '*raptor*' -type f -exec strings {} \; | grep -i 'raptor.*version'Verify Fix Applied:
Verify version is 2.0.16 or higher: raptor-config --version | grep -q '^2\.0\.1[6-9]\|^2\.0\.2'📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults
- Memory corruption errors in application logs
- Unusual RDF/XML processing patterns
Network Indicators:
- Unusually large or malformed RDF/XML payloads to RDF processing endpoints
- Repeated connection attempts to RDF services
SIEM Query:
source="application.log" ("segmentation fault" OR "buffer overflow" OR "raptor") AND ("RDF" OR "XML")🔗 References
- http://www.openwall.com/lists/oss-security/2020/11/13/1
- http://www.openwall.com/lists/oss-security/2020/11/13/2
- http://www.openwall.com/lists/oss-security/2020/11/14/2
- http://www.openwall.com/lists/oss-security/2020/11/16/2
- http://www.openwall.com/lists/oss-security/2020/11/16/3
- https://github.com/LibreOffice/core/blob/master/external/redland/raptor/0001-Calcualte-max-nspace-declarations-correctly-for-XML-.patch.1
- https://lists.debian.org/debian-lts-announce/2020/11/msg00012.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RD67AVORGQXORPWNYYUHCH6YPPT6CI4O/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RVHFYQDMVEBICIL4DBAGRRLPUR4QYWMV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDZRNM45VPTQF2BKRWG4YRCHJGQ2L7NS/
- https://www.debian.org/security/2020/dsa-4785
- https://www.openwall.com/lists/oss-security/2017/06/07/1
- http://www.openwall.com/lists/oss-security/2020/11/13/1
- http://www.openwall.com/lists/oss-security/2020/11/13/2
- http://www.openwall.com/lists/oss-security/2020/11/14/2
- http://www.openwall.com/lists/oss-security/2020/11/16/2
- http://www.openwall.com/lists/oss-security/2020/11/16/3
- https://github.com/LibreOffice/core/blob/master/external/redland/raptor/0001-Calcualte-max-nspace-declarations-correctly-for-XML-.patch.1
- https://lists.debian.org/debian-lts-announce/2020/11/msg00012.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RD67AVORGQXORPWNYYUHCH6YPPT6CI4O/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RVHFYQDMVEBICIL4DBAGRRLPUR4QYWMV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDZRNM45VPTQF2BKRWG4YRCHJGQ2L7NS/
- https://www.debian.org/security/2020/dsa-4785
- https://www.openwall.com/lists/oss-security/2017/06/07/1
