CVE-2025-3857
📋 TL;DR
CVE-2025-3857 is a denial-of-service vulnerability in Amazon.IonDotnet's RawBinaryReader class that occurs when processing malformed or truncated binary Ion data. The lack of proper byte count validation triggers an infinite loop, potentially causing application crashes or resource exhaustion. This affects any .NET application using vulnerable versions of Amazon.IonDotnet to parse Ion data from untrusted sources.
💻 Affected Systems
- Amazon.IonDotnet
⚠️ 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 denial of service through infinite loop causing 100% CPU utilization, memory exhaustion, and application crashes affecting all users of the vulnerable service.
Likely Case
Application instability and crashes when processing malformed Ion data from external sources, leading to service disruption.
If Mitigated
Minimal impact with proper input validation and patching, though some performance degradation may occur when rejecting malformed data.
🎯 Exploit Status
Exploitation requires sending malformed binary Ion data to vulnerable applications. No authentication needed if application accepts external Ion data.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.3.1
Vendor Advisory: https://github.com/amazon-ion/ion-dotnet/security/advisories/GHSA-gm2p-wf5c-w3pj
Restart Required: Yes
Instructions:
1. Update NuGet package reference to Amazon.IonDotnet version 1.3.1 or later. 2. Rebuild and redeploy affected applications. 3. Test Ion data processing functionality after update.
🔧 Temporary Workarounds
Input Validation Filter
allImplement custom validation to check Ion data integrity before passing to RawBinaryReader
// C# example: Validate Ion data length before processing
if (ionData.Length < minimumValidLength) { throw new InvalidDataException(); }
Use Text Ion Format
allConvert to text Ion format processing if binary format not required
// Use IonReaderText instead of RawBinaryReader for text Ion data
🧯 If You Can't Patch
- Implement network-level filtering to block or rate-limit Ion data from untrusted sources
- Deploy application monitoring with alerting for abnormal CPU/memory usage patterns
🔍 How to Verify
Check if Vulnerable:
Check NuGet package reference or assembly version for Amazon.IonDotnet < 1.3.1Check Version:
dotnet list package | findstr Amazon.IonDotnetVerify Fix Applied:
Confirm Amazon.IonDotnet version is 1.3.1 or higher in package references and deployed assemblies📡 Detection & Monitoring
Log Indicators:
- High CPU usage spikes
- Application crashes with stack traces mentioning RawBinaryReader
- OutOfMemoryException events
Network Indicators:
- Unusually large or malformed Ion data payloads
- Repeated Ion data submissions to vulnerable endpoints
SIEM Query:
source="application_logs" AND ("RawBinaryReader" OR "Amazon.IonDotnet") AND ("high cpu" OR "out of memory" OR "infinite loop")