CVE-2019-6978
📋 TL;DR
CVE-2019-6978 is a double-free vulnerability in LibGD graphics library that allows attackers to execute arbitrary code or cause denial of service by processing specially crafted image files. It affects applications using vulnerable LibGD versions for image processing. PHP applications are not affected as noted in the CVE description.
💻 Affected Systems
- LibGD (GD Graphics Library)
- Applications using LibGD for image processing
📦 What is this software?
Libgd by Libgd
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Application crash causing denial of service, potentially leading to service disruption.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially just application instability.
🎯 Exploit Status
Exploitation requires processing a malicious image file through vulnerable functions. Public proof-of-concept exists in GitHub issues.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: LibGD 2.2.6 or later
Vendor Advisory: https://access.redhat.com/errata/RHSA-2019:2722
Restart Required: Yes
Instructions:
1. Update LibGD to version 2.2.6 or later. 2. Rebuild applications linked against LibGD. 3. Restart affected services. 4. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade libgd3' (Debian/Ubuntu) or 'sudo yum update libgd' (RHEL/CentOS).
🔧 Temporary Workarounds
Disable vulnerable image formats
allConfigure applications to disable processing of GIF, JPEG, or WBMP formats if not required.
Application-specific configuration changes
Input validation and sanitization
allImplement strict validation of image files before processing with LibGD.
Implement file type verification, size limits, and magic byte checking
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable systems from untrusted networks
- Deploy web application firewall (WAF) with rules to block malicious image uploads
🔍 How to Verify
Check if Vulnerable:
Check LibGD version: 'gdlib-config --version' or 'dpkg -l | grep libgd' or 'rpm -qa | grep libgd'. If version is 2.2.5 or earlier, system is vulnerable.Check Version:
gdlib-config --version 2>/dev/null || dpkg -l | grep libgd | awk '{print $3}' || rpm -qa | grep libgd | cut -d'-' -f2-Verify Fix Applied:
Verify LibGD version is 2.2.6 or later using same commands. Test image processing functionality remains operational.📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults
- Memory corruption errors in application logs
- Failed image processing operations
Network Indicators:
- Unusual image upload patterns
- Multiple failed image processing requests
SIEM Query:
source="application.logs" AND ("segmentation fault" OR "double free" OR "corrupted") AND process="*gd*"🔗 References
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00025.html
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00031.html
- https://access.redhat.com/errata/RHSA-2019:2722
- https://github.com/libgd/libgd/commit/553702980ae89c83f2d6e254d62cf82e204956d0
- https://github.com/libgd/libgd/issues/492
- https://github.com/php/php-src/commit/089f7c0bc28d399b0420aa6ef058e4c1c120b2ae
- https://lists.debian.org/debian-lts-announce/2019/01/msg00028.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3CZ2QADQTKRHTGB2AHD7J4QQNDLBEMM6/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3WRUPZVT2MWFUEMVGTRAGDOBHLNMGK5R/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEYUUOW75YD3DENIPYMO263E6NL2NFHI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TTXSLRZI5BCQT3H5KALG3DHUWUMNPDX2/
- https://security.gentoo.org/glsa/201903-18
- https://usn.ubuntu.com/3900-1/
- https://www.debian.org/security/2019/dsa-4384
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00025.html
- http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00031.html
- https://access.redhat.com/errata/RHSA-2019:2722
- https://github.com/libgd/libgd/commit/553702980ae89c83f2d6e254d62cf82e204956d0
- https://github.com/libgd/libgd/issues/492
- https://github.com/php/php-src/commit/089f7c0bc28d399b0420aa6ef058e4c1c120b2ae
- https://lists.debian.org/debian-lts-announce/2019/01/msg00028.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3CZ2QADQTKRHTGB2AHD7J4QQNDLBEMM6/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3WRUPZVT2MWFUEMVGTRAGDOBHLNMGK5R/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEYUUOW75YD3DENIPYMO263E6NL2NFHI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TTXSLRZI5BCQT3H5KALG3DHUWUMNPDX2/
- https://security.gentoo.org/glsa/201903-18
- https://usn.ubuntu.com/3900-1/
- https://www.debian.org/security/2019/dsa-4384
