CVE-2025-55398
📋 TL;DR
A vulnerability in mouse07410 asn1c through version 0.9.29 allows attackers to bypass INTEGER constraints in UPER decoders when bounds exceed 32 bits, potentially leading to incorrect processing of malicious input. This affects any software using asn1c-generated code for ASN.1 data parsing with UPER encoding.
💻 Affected Systems
- mouse07410 asn1c
- Software using asn1c-generated UPER decoders
⚠️ 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
Remote code execution or system compromise through specially crafted ASN.1 data that bypasses validation checks, potentially leading to complete system takeover.
Likely Case
Denial of service, data corruption, or privilege escalation through malformed ASN.1 input that triggers unexpected behavior in applications using vulnerable decoders.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially causing application crashes or minor data integrity issues.
🎯 Exploit Status
Exploitation requires crafting malicious ASN.1 data that triggers the constraint bypass, but no public exploit code is currently available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after 0.9.29
Vendor Advisory: https://github.com/mouse07410/asn1c/issues/222
Restart Required: Yes
Instructions:
1. Update asn1c to latest version. 2. Regenerate all UPER decoder code using updated asn1c. 3. Recompile and redeploy affected applications. 4. Restart services using updated code.
🔧 Temporary Workarounds
Input validation wrapper
allImplement additional input validation for ASN.1 data before passing to vulnerable decoders
Disable UPER encoding
allSwitch to alternative ASN.1 encoding rules if possible
🧯 If You Can't Patch
- Implement network segmentation to isolate systems using vulnerable asn1c code
- Deploy application firewalls with ASN.1 protocol inspection capabilities
🔍 How to Verify
Check if Vulnerable:
Check if asn1c version is 0.9.29 or earlier and if applications use UPER decoders for INTEGER types with bounds > 32 bitsCheck Version:
asn1c --versionVerify Fix Applied:
Verify asn1c version is newer than 0.9.29 and regenerated decoders properly enforce INTEGER constraints📡 Detection & Monitoring
Log Indicators:
- Application crashes during ASN.1 parsing
- Unexpected integer values in decoded data
- Memory access violations in decoder functions
Network Indicators:
- Unusually large or malformed ASN.1 packets
- Protocol anomalies in ASN.1-encoded communications
SIEM Query:
source="application_logs" AND ("asn1" OR "uper") AND ("crash" OR "exception" OR "overflow")