CVE-2024-21909
📋 TL;DR
PeterO.Cbor versions 4.0.0 through 4.5.0 contain a denial of service vulnerability where specially crafted CBOR data can crash applications using the library's decoding functions. This affects any application that processes untrusted CBOR data using these vulnerable versions. Remote attackers could potentially cause service disruption without authentication.
💻 Affected Systems
- PeterO.Cbor library
📦 What is this software?
Cbor by Peteroupc
⚠️ Risk & Real-World Impact
Worst Case
Complete application crash or unresponsive service requiring restart, potentially affecting availability of critical systems processing CBOR data from untrusted sources.
Likely Case
Application instability or crashes when processing malicious CBOR payloads, leading to service disruption and potential data loss in active transactions.
If Mitigated
Minimal impact if input validation and rate limiting are implemented, with proper monitoring to detect and block malicious payloads.
🎯 Exploit Status
The advisory indicates remote unauthenticated exploitation is possible. Crafting malicious CBOR data requires understanding of the vulnerability but appears straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.5.1
Vendor Advisory: https://github.com/peteroupc/CBOR/security/advisories/GHSA-6r92-cgxc-r5fg
Restart Required: Yes
Instructions:
1. Update PeterO.Cbor NuGet package to version 4.5.1 or later. 2. Rebuild and redeploy affected applications. 3. Restart services using the updated library.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation for CBOR data before passing to DecodeFromBytes or other decoding functions
Rate limiting and monitoring
allImplement rate limiting on CBOR processing endpoints and monitor for abnormal patterns
🧯 If You Can't Patch
- Implement network-level filtering to block or limit CBOR data from untrusted sources
- Deploy application-level monitoring with automatic restart capabilities for crash detection
🔍 How to Verify
Check if Vulnerable:
Check project dependencies for PeterO.Cbor version 4.0.0-4.5.0. For .NET projects, examine packages.config or .csproj files.Check Version:
For NuGet: `dotnet list package` or check packages.config for <package id="PeterO.Cbor" version="..." />Verify Fix Applied:
Verify PeterO.Cbor version is 4.5.1 or later in package dependencies and application is using the updated library.📡 Detection & Monitoring
Log Indicators:
- Application crashes or unhandled exceptions in CBOR decoding functions
- High error rates in CBOR processing endpoints
- Abnormal memory usage patterns
Network Indicators:
- Unusually large or malformed CBOR payloads
- High volume of CBOR requests to vulnerable endpoints
SIEM Query:
source="application_logs" AND ("DecodeFromBytes" OR "CBOR" OR "PeterO.Cbor") AND ("crash" OR "exception" OR "error")🔗 References
- https://github.com/advisories/GHSA-6r92-cgxc-r5fg
- https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95
- https://github.com/peteroupc/CBOR/compare/v4.5...v4.5.1
- https://github.com/peteroupc/CBOR/security/advisories/GHSA-6r92-cgxc-r5fg
- https://vulncheck.com/advisories/vc-advisory-GHSA-6r92-cgxc-r5fg
- https://github.com/advisories/GHSA-6r92-cgxc-r5fg
- https://github.com/peteroupc/CBOR/commit/b4117dbbb4cd5a4a963f9d0c9aa132f033e15b95
- https://github.com/peteroupc/CBOR/compare/v4.5...v4.5.1
- https://github.com/peteroupc/CBOR/security/advisories/GHSA-6r92-cgxc-r5fg
- https://vulncheck.com/advisories/vc-advisory-GHSA-6r92-cgxc-r5fg
