CVE-2026-2016
📋 TL;DR
A stack-based buffer overflow vulnerability exists in libfastcommon's base64_decode function, allowing local attackers to execute arbitrary code or cause denial of service. This affects systems using libfastcommon up to version 1.0.84. The vulnerability requires local access to exploit.
💻 Affected Systems
- happyfish100 libfastcommon
📦 What is this software?
Libfastcommon by Happyfish100
⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation leading to full system compromise, arbitrary code execution, or persistent backdoor installation.
Likely Case
Local denial of service (crash) or limited code execution within the context of the vulnerable application.
If Mitigated
Minimal impact if proper privilege separation and sandboxing are implemented.
🎯 Exploit Status
Exploit has been publicly disclosed and requires local access. Attackers need to trigger the vulnerable base64_decode function with malicious input.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.85 or later (commit 82f66af3e252e3e137dba0c3891570f085e79adf)
Vendor Advisory: https://github.com/happyfish100/libfastcommon/issues/55
Restart Required: Yes
Instructions:
1. Update libfastcommon to version 1.0.85 or later. 2. Recompile any applications using libfastcommon. 3. Restart affected services.
🔧 Temporary Workarounds
Disable or restrict local access
allLimit local user access to systems running vulnerable libfastcommon versions
Application sandboxing
linuxRun applications using libfastcommon in restricted containers or sandboxes
docker run --security-opt=no-new-privileges -it application_image
🧯 If You Can't Patch
- Implement strict access controls to limit local user privileges
- Monitor for suspicious local process activity and privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check libfastcommon version: find / -name "*libfastcommon*" -type f 2>/dev/null | xargs strings 2>/dev/null | grep -i versionCheck Version:
strings /usr/lib/libfastcommon.so | grep -i versionVerify Fix Applied:
Verify version is 1.0.85 or later and commit 82f66af3e252e3e137dba0c3891570f085e79adf is present📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults
- Unusual local process spawning
- Privilege escalation attempts
Network Indicators:
- None - local exploit only
SIEM Query:
Process creation from unexpected local users OR Application crash logs containing libfastcommon/base64 references🔗 References
- https://github.com/happyfish100/libfastcommon/
- https://github.com/happyfish100/libfastcommon/commit/82f66af3e252e3e137dba0c3891570f085e79adf
- https://github.com/happyfish100/libfastcommon/issues/55
- https://github.com/happyfish100/libfastcommon/issues/55#issue-3836362577
- https://github.com/happyfish100/libfastcommon/issues/55#issuecomment-3776757848
- https://vuldb.com/?ctiid.344598
- https://vuldb.com/?id.344598
- https://vuldb.com/?submit.743873
