CVE-2026-23490
📋 TL;DR
This vulnerability in pyasn1 allows attackers to cause denial-of-service through memory exhaustion by sending malformed RELATIVE-OID data with excessive continuation octets. Any Python application using pyasn1 versions before 0.6.2 that processes untrusted ASN.1 data is affected. This could impact systems that parse certificates, network protocols, or other ASN.1 encoded data from external sources.
💻 Affected Systems
- pyasn1 library
- Any Python application using pyasn1
⚠️ 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
Complete service unavailability due to memory exhaustion, potentially requiring system restart and causing extended downtime.
Likely Case
Service degradation or temporary unavailability affecting applications that process ASN.1 data from untrusted sources.
If Mitigated
Minimal impact if proper input validation and resource limits are in place, or if ASN.1 data only comes from trusted sources.
🎯 Exploit Status
Exploitation requires sending malformed ASN.1 data to vulnerable applications. No public exploit code is known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.6.2
Vendor Advisory: https://github.com/pyasn1/pyasn1/security/advisories/GHSA-63vm-454h-vhhq
Restart Required: No
Instructions:
1. Update pyasn1 to version 0.6.2 or later using pip: pip install --upgrade pyasn1 2. Verify the update was successful: pip show pyasn1 3. Restart any Python applications using pyasn1 to load the updated library.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation for ASN.1 data before passing to pyasn1 library
Resource limiting
linuxConfigure memory limits on processes using pyasn1 to prevent complete exhaustion
ulimit -v [memory_limit_in_kb] # Linux example
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable systems
- Deploy WAF or application firewall rules to block malformed ASN.1 data patterns
🔍 How to Verify
Check if Vulnerable:
Check pyasn1 version: python -c "import pyasn1; print(pyasn1.__version__)" - if version is less than 0.6.2, system is vulnerable.Check Version:
python -c "import pyasn1; print(pyasn1.__version__)"Verify Fix Applied:
Verify pyasn1 version is 0.6.2 or higher: python -c "import pyasn1; print(pyasn1.__version__)"📡 Detection & Monitoring
Log Indicators:
- Memory exhaustion errors
- Process crashes or restarts
- High memory usage spikes in Python processes
Network Indicators:
- Unusual ASN.1 data patterns in network traffic
- Repeated malformed data packets to services using pyasn1
SIEM Query:
source="application_logs" AND ("memory exhausted" OR "out of memory" OR "pyasn1" OR "ASN.1")