CVE-2025-71263
📋 TL;DR
A buffer overflow vulnerability exists in the su command of UNIX Fourth Research Edition (v4) due to a fixed-size 100-byte password buffer. Local users can exploit this to execute arbitrary code and gain root privileges. Only systems running the historical UNIX v4 in lab environments are affected.
💻 Affected Systems
- UNIX Fourth Research Edition
⚠️ 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
Local attacker gains full root privileges, compromising the entire system and potentially pivoting to other systems.
Likely Case
Limited impact due to extremely rare deployment of UNIX v4; mostly academic/lab environments affected.
If Mitigated
No impact if system isn't running UNIX v4 or has access controls preventing local user execution.
🎯 Exploit Status
Exploitation requires local user access; buffer overflow is straightforward given fixed buffer size.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: N/A
Restart Required: No
Instructions:
No official patch exists for this historical system. Consider upgrading to modern UNIX-like systems or implementing workarounds.
🔧 Temporary Workarounds
Replace su with sudo
linuxReplace vulnerable su command with sudo implementation that properly validates input
# Replace /bin/su with secure alternative
# Example: install sudo and configure /etc/sudoers
Remove su setuid bit
allRemove privilege escalation capability from su command
chmod u-s /bin/su
🧯 If You Can't Patch
- Restrict local user access to systems running UNIX v4
- Monitor for unusual su command usage or privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check if system is running UNIX Fourth Research Edition v4 and examine su binary for fixed buffer sizeCheck Version:
uname -aVerify Fix Applied:
Verify su binary has been replaced or setuid bit removed📡 Detection & Monitoring
Log Indicators:
- Multiple failed su attempts followed by successful privilege escalation
- Unusual process execution from su command
Network Indicators:
- N/A - local exploit only
SIEM Query:
process.name:"su" AND event.action:"executed" AND user.name NOT IN ["root", "authorized_users"]