CVE-2021-32810 – A race condition in crossbeam-deque Rust librar... (How to Fix)

Q: How do I fix CVE-2021-32810?

1. Update Cargo.toml to require crossbeam-deque >=0.7.4 or >=0.8.1. 2. Run 'cargo update crossbeam-deque'. 3. Rebuild and redeploy affected Rust applications.

Q: What is the severity of CVE-2021-32810?

CVE-2021-32810 has a CVSS score of 9.8 (CRITICAL). A race condition in crossbeam-deque Rust library versions before 0.7.4 and 0.8.0 allows tasks in worker queues to be popped twice while other tasks are forgotten. This can cause double-free memory corruption if tasks are heap-allocated, leading to crashes or memory leaks. Any Rust application using crossbeam-deque's Stealer methods for task scheduling is affected.

📋 TL;DR

A race condition in crossbeam-deque Rust library versions before 0.7.4 and 0.8.0 allows tasks in worker queues to be popped twice while other tasks are forgotten. This can cause double-free memory corruption if tasks are heap-allocated, leading to crashes or memory leaks. Any Rust application using crossbeam-deque's Stealer methods for task scheduling is affected.

💻 Affected Systems

Products:

crossbeam-deque Rust library

Versions: Versions <0.7.4 and 0.8.x <0.8.1

Operating Systems: All operating systems running Rust applications

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects Rust applications using crossbeam-deque's Stealer::steal, Stealer::steal_batch, or Stealer::steal_batch_and_pop methods.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Double-free memory corruption leading to arbitrary code execution, denial of service, or data corruption in affected Rust applications.

🟠

Likely Case

Application crashes, memory leaks, or logical bugs causing incorrect task execution in multi-threaded Rust programs.

🟢

If Mitigated

Minor performance impact or task scheduling anomalies if proper memory safety practices are followed.

🌐 Internet-Facing: MEDIUM - Exploitation requires specific conditions in affected Rust services, but impact could be severe.

🏢 Internal Only: MEDIUM - Same technical risk as internet-facing, but reduced attack surface from external actors.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: HIGH - Requires race condition triggering in multi-threaded context

Exploitation depends on specific application usage patterns and timing conditions.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 0.7.4 or 0.8.1

Vendor Advisory: https://github.com/crossbeam-rs/crossbeam/security/advisories/GHSA-pqqp-xmhj-wgcw

Restart Required: Yes

Instructions:

1. Update Cargo.toml to require crossbeam-deque >=0.7.4 or >=0.8.1. 2. Run 'cargo update crossbeam-deque'. 3. Rebuild and redeploy affected Rust applications.

🔧 Temporary Workarounds

Avoid affected Stealer methods

all

Temporarily modify code to avoid using Stealer::steal, Stealer::steal_batch, or Stealer::steal_batch_and_pop methods

🧯 If You Can't Patch

Isolate affected applications in restricted environments with minimal privileges
Implement additional monitoring for memory corruption or application crashes

🔍 How to Verify

Check if Vulnerable:

Check Cargo.lock or run 'cargo tree | grep crossbeam-deque' to see installed version

Check Version:

grep crossbeam-deque Cargo.lock

Verify Fix Applied:

Verify crossbeam-deque version is >=0.7.4 or >=0.8.1 in Cargo.lock after update

📡 Detection & Monitoring

Log Indicators:

Application crashes with memory corruption errors
Unexpected double-free warnings in Rust panic messages

Network Indicators:

Service disruptions or unexpected restarts of affected applications

SIEM Query:

Application logs containing 'double free', 'memory corruption', or crossbeam-deque related panic messages

📊 Metadata

CVE ID: CVE-2021-32810

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-362

Published: August 2, 2021

Last Updated: November 21, 2024

🔗 References

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