CVE-2021-41220
📋 TL;DR
This CVE describes a memory leak and use-after-free vulnerability in TensorFlow's CollectiveReduceV2 async implementation. Attackers could potentially cause denial of service or execute arbitrary code by exploiting these memory management flaws. Only TensorFlow 2.6.1 is affected, as the vulnerability was introduced and fixed within a short timeframe.
💻 Affected Systems
- TensorFlow
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data exfiltration, or lateral movement within the infrastructure.
Likely Case
Denial of service through memory exhaustion or application crashes, potentially disrupting machine learning workflows and services.
If Mitigated
Limited impact with proper memory isolation and containerization, though service disruption remains possible.
🎯 Exploit Status
Exploitation requires triggering specific async CollectiveReduceV2 operations. No public exploits have been documented, but the memory corruption nature makes weaponization plausible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: TensorFlow 2.6.1 with cherry-picked fix or TensorFlow 2.7.0+
Vendor Advisory: https://github.com/tensorflow/tensorflow/security/advisories/GHSA-gpfh-jvf9-7wg5
Restart Required: Yes
Instructions:
1. Upgrade to TensorFlow 2.7.0 or later. 2. For TensorFlow 2.6.1, apply the cherry-picked commit ca38dab9d3ee66c5de06f11af9a4b1200da5ef75. 3. Restart all TensorFlow services and applications.
🔧 Temporary Workarounds
Disable async CollectiveReduceV2
allAvoid using async implementation of CollectiveReduceV2 operations if possible
Configure TensorFlow to use synchronous collective operations instead
🧯 If You Can't Patch
- Isolate TensorFlow instances in containers with memory limits to contain potential memory exhaustion
- Implement network segmentation to limit TensorFlow service exposure to only trusted clients
🔍 How to Verify
Check if Vulnerable:
Check TensorFlow version: if running exactly 2.6.1 and using CollectiveReduceV2 with async operations, system is vulnerable.Check Version:
python -c "import tensorflow as tf; print(tf.__version__)"Verify Fix Applied:
Verify TensorFlow version is 2.7.0+ or confirm commit ca38dab9d3ee66c5de06f11af9a4b1200da5ef75 is present in 2.6.1 installation.📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes
- Memory exhaustion alerts
- Repeated CollectiveReduceV2 operation failures
Network Indicators:
- Unusual traffic patterns to TensorFlow serving endpoints
- Connection spikes followed by service degradation
SIEM Query:
source="tensorflow" AND (event="crash" OR event="oom" OR event="memory_exhaustion")🔗 References
- https://github.com/tensorflow/tensorflow/commit/ca38dab9d3ee66c5de06f11af9a4b1200da5ef75
- https://github.com/tensorflow/tensorflow/security/advisories/GHSA-gpfh-jvf9-7wg5
- https://github.com/tensorflow/tensorflow/commit/ca38dab9d3ee66c5de06f11af9a4b1200da5ef75
- https://github.com/tensorflow/tensorflow/security/advisories/GHSA-gpfh-jvf9-7wg5
