CVE-2025-11683
📋 TL;DR
YAML::Syck versions before 1.36 for Perl have a missing null-terminator vulnerability in token.c that causes out-of-bounds reads when processing complex YAML files with hashes containing all keys and empty values. This allows reading adjacent memory variables, potentially disclosing sensitive information. Systems using vulnerable YAML::Syck versions in Perl applications are affected.
💻 Affected Systems
- YAML::Syck for Perl
⚠️ 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
Information disclosure of adjacent memory contents, potentially exposing sensitive data like passwords, tokens, or application secrets stored in memory.
Likely Case
Limited information disclosure of adjacent variable values within the module's allocated memory, possibly revealing internal application state.
If Mitigated
No impact if patched or if vulnerable functionality is not used with triggering YAML files.
🎯 Exploit Status
Requires crafting specific YAML input to trigger the out-of-bounds read; no known public exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.36 and later
Vendor Advisory: https://metacpan.org/dist/YAML-Syck/changes
Restart Required: No
Instructions:
1. Update YAML::Syck via CPAN: 'cpan YAML::Syck' 2. Or install from source: download version 1.36+ from CPAN 3. Verify installation with 'perl -MYAML::Syck -e "print $YAML::Syck::VERSION"'
🔧 Temporary Workarounds
Input Validation
allValidate or sanitize YAML input to prevent processing of complex hashes with empty values.
Use Alternative Parser
allSwitch to YAML::XS or other YAML parsers if feasible.
cpan YAML::XS
🧯 If You Can't Patch
- Implement strict input validation to reject complex YAML structures with hashes containing all keys and empty values.
- Monitor application logs for errors or unusual behavior when processing YAML files.
🔍 How to Verify
Check if Vulnerable:
Check YAML::Syck version: 'perl -MYAML::Syck -e "print $YAML::Syck::VERSION"' - if output is less than 1.36, system is vulnerable.Check Version:
perl -MYAML::Syck -e "print $YAML::Syck::VERSION"Verify Fix Applied:
After update, run same command to confirm version is 1.36 or higher.📡 Detection & Monitoring
Log Indicators:
- Application errors or crashes when parsing YAML files
- Unusual memory access patterns in debug logs
Network Indicators:
- Inbound requests containing YAML payloads with complex hash structures
SIEM Query:
source="application.logs" AND ("YAML::Syck" OR "YAML parsing error")