CVE-2024-56406
📋 TL;DR
A heap buffer overflow vulnerability in Perl's tr operator when processing non-ASCII characters allows attackers to crash applications or potentially execute arbitrary code. This affects Perl versions 5.34 through 5.40, including development versions, impacting any system running vulnerable Perl scripts.
💻 Affected Systems
- Perl programming language
📦 What is this software?
Perl by Perl
Perl by Perl
Perl by Perl
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise on platforms without memory protection features like ASLR.
Likely Case
Denial of service through application crashes when processing malicious input in Perl scripts.
If Mitigated
Application crash without code execution on modern systems with ASLR and other memory protections.
🎯 Exploit Status
Proof-of-concept demonstrating crash is publicly available. Code execution would require additional exploitation techniques.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.38.4, 5.40.2, and later versions
Vendor Advisory: https://metacpan.org/release/SHAY/perl-5.38.4/changes
Restart Required: No
Instructions:
1. Update Perl using your system package manager (apt-get upgrade perl, yum update perl, etc.) 2. For custom installations, download and compile from perl.org 3. Verify the update with 'perl -v'
🔧 Temporary Workarounds
Input validation for tr operator
allValidate or sanitize input before using the tr operator with non-ASCII characters
# Add input validation in Perl scripts before using tr operator
🧯 If You Can't Patch
- Implement strict input validation for all Perl scripts processing user data
- Use application firewalls or WAF rules to block suspicious patterns in input to Perl applications
🔍 How to Verify
Check if Vulnerable:
Run: perl -e '$_ = "\x{FF}" x 1000000; tr/\xFF/\x{100}/;' - if it crashes, system is vulnerableCheck Version:
perl -v | head -2Verify Fix Applied:
Run the same test command - it should complete without segmentation fault📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors in application logs
- Unexpected Perl process crashes
Network Indicators:
- HTTP requests containing repeated non-ASCII characters to Perl-based applications
SIEM Query:
source="application.log" AND "segmentation fault" AND process="perl"🔗 References
- https://github.com/Perl/perl5/commit/87f42aa0e0096e9a346c9672aa3a0bd3bef8c1dd.patch
- https://metacpan.org/release/SHAY/perl-5.38.4/changes
- https://metacpan.org/release/SHAY/perl-5.40.2/changes
- http://www.openwall.com/lists/oss-security/2025/04/13/3
- http://www.openwall.com/lists/oss-security/2025/04/13/4
- http://www.openwall.com/lists/oss-security/2025/04/13/5
