CVE-2021-26305
📋 TL;DR
CVE-2021-26305 is a deserialization vulnerability in the cdr crate for Rust that allows a malicious Read implementation to access uninitialized heap memory. This violates Rust's memory safety guarantees and could lead to information disclosure or memory corruption. Any Rust application using cdr versions before 0.2.4 for deserialization is affected.
💻 Affected Systems
- cdr crate for Rust
📦 What is this software?
Cdr by Cdr Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution through memory corruption leading to complete system compromise
Likely Case
Information disclosure of sensitive data from uninitialized memory, potentially including credentials or cryptographic material
If Mitigated
Limited impact with proper input validation and sandboxing, but still violates Rust's safety guarantees
🎯 Exploit Status
Exploitation requires a malicious Read implementation, but the vulnerability is in a fundamental deserialization primitive
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: cdr 0.2.4 and later
Vendor Advisory: https://rustsec.org/advisories/RUSTSEC-2021-0012.html
Restart Required: Yes
Instructions:
1. Update Cargo.toml to require cdr >= 0.2.4
2. Run 'cargo update' to fetch the patched version
3. Rebuild and redeploy your application
4. Test that deserialization functionality still works correctly
🔧 Temporary Workarounds
Avoid user-provided Read implementations
allModify code to avoid passing user-controlled Read implementations to Deserializer::read_vec
Use alternative serialization crate
allTemporarily switch to a different serialization library like serde or bincode
cargo remove cdr
cargo add serde
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all deserialization inputs
- Isolate deserialization code in separate processes or containers with minimal privileges
🔍 How to Verify
Check if Vulnerable:
Check Cargo.lock or run 'cargo tree | grep cdr' to see if cdr version < 0.2.4 is usedCheck Version:
grep -A2 'name = "cdr"' Cargo.lockVerify Fix Applied:
Verify cdr version is >= 0.2.4 in Cargo.lock and test deserialization with edge cases📡 Detection & Monitoring
Log Indicators:
- Unusual memory access patterns
- Deserialization errors with malformed input
- Process crashes during deserialization
Network Indicators:
- Unexpected data patterns in serialized streams
- Abnormal traffic to deserialization endpoints
SIEM Query:
process.name:your_app AND (event.type:crash OR memory.usage:spike) AND process.args:*deserialize*