CVE-2023-5156
📋 TL;DR
CVE-2023-5156 is a memory leak vulnerability in the GNU C Library (glibc) introduced by a previous fix for CVE-2023-4806. This flaw can cause applications to crash due to memory exhaustion, affecting any system using vulnerable glibc versions. All applications linked against glibc are potentially impacted.
💻 Affected Systems
- GNU C Library (glibc)
📦 What is this software?
Glibc by Gnu
The GNU C Library (glibc) is the core C library for Linux systems, providing essential system calls and basic functions for all C programs. It is a fundamental component that nearly every Linux application depends on.
Learn more about Glibc →⚠️ Risk & Real-World Impact
Worst Case
Denial of service through application crashes, potentially affecting critical system services and leading to system instability or downtime.
Likely Case
Intermittent application crashes under specific conditions, particularly in applications that trigger the affected code path frequently.
If Mitigated
Minimal impact with proper monitoring and restart mechanisms in place for affected applications.
🎯 Exploit Status
Exploitation requires applications to trigger the memory leak repeatedly, leading to resource exhaustion over time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: glibc versions with the fix for CVE-2023-5156 (after commit addressing the memory leak)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2023-5156
Restart Required: Yes
Instructions:
1. Update glibc package using your distribution's package manager. 2. For Red Hat/CentOS/Fedora: 'sudo yum update glibc'. 3. For Debian/Ubuntu: 'sudo apt update && sudo apt upgrade libc6'. 4. Restart affected applications or reboot the system.
🔧 Temporary Workarounds
Monitor and restart applications
linuxImplement monitoring for memory usage and automatically restart applications showing abnormal memory growth
🧯 If You Can't Patch
- Implement application monitoring with alerts for memory leaks
- Schedule regular application restarts to clear accumulated memory
🔍 How to Verify
Check if Vulnerable:
Check glibc version and verify if it contains the problematic commit but lacks the fix: 'ldd --version' and compare with vendor advisoriesCheck Version:
ldd --version | head -1Verify Fix Applied:
Verify glibc version is updated to a version containing the CVE-2023-5156 fix: 'rpm -q glibc' (RHEL) or 'dpkg -l libc6' (Debian/Ubuntu)📡 Detection & Monitoring
Log Indicators:
- Application crashes with out-of-memory errors
- Increased memory usage in application logs
- System logs showing process termination due to memory exhaustion
Network Indicators:
- Service unavailability
- Increased latency or timeouts from affected applications
SIEM Query:
source="application_logs" AND ("out of memory" OR "memory leak" OR "segmentation fault")🔗 References
- https://access.redhat.com/security/cve/CVE-2023-5156
- https://bugzilla.redhat.com/show_bug.cgi?id=2240541
- https://sourceware.org/bugzilla/show_bug.cgi?id=30884
- https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=ec6b95c3303c700eb89eebeda2d7264cc184a796
- http://www.openwall.com/lists/oss-security/2023/10/03/4
- http://www.openwall.com/lists/oss-security/2023/10/03/5
- http://www.openwall.com/lists/oss-security/2023/10/03/6
- http://www.openwall.com/lists/oss-security/2023/10/03/8
- https://access.redhat.com/security/cve/CVE-2023-5156
- https://bugzilla.redhat.com/show_bug.cgi?id=2240541
- https://security.gentoo.org/glsa/202402-01
- https://sourceware.org/bugzilla/show_bug.cgi?id=30884
- https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=ec6b95c3303c700eb89eebeda2d7264cc184a796
