crossbeam-channel: double-free race condition in crossbeam-channel Rust crate (CVE-2025-4574) #shorts

Summary

Welcome to today’s security update. We’re discussing CVE-2025-4574, a recently disclosed vulnerability in the crossbeam-channel crate for Rust. First published on May 13, 2025 and updated through May 21, it involves a race condition in the channel drop logic leading to a possible double-free and memory corruption. Fedora 41 has already shipped a fix in the python-watchfiles package, and Red Hat has pushed updates across multiple enterprise products.

Product details

crossbeam-channel is a popular Rust library that provides multi-producer, multi-consumer channels for thread communication. Version 0.5.12 and any release prior to 0.5.15 are affected. Fedora 41 maintainers updated the python-watchfiles package—which depends indirectly on crossbeam-channel—to pull in the fixed version. Red Hat has similarly issued patches for Directory Server, Enterprise Linux versions 7 through 10, OpenShift Container Platform 4, Satellite 6 and other components.

Vulnerability type summary

This issue is classified as a double-free vulnerability caused by a race condition. In concurrent code, if two threads trigger the channel’s drop logic simultaneously, the same memory region can be freed twice. Double-free bugs can lead to memory corruption, application crashes, and in some cases can be leveraged for arbitrary code execution.

Details of the vulnerability

The flaw resides in the internal Channel type’s Drop implementation. When a Channel instance is dropped, cleanup code deallocates shared buffers. Under heavy concurrency, however, two threads can reach that cleanup path at the same time for the same channel object. Because Rust’s ownership rules are bypassed in the unsafe cleanup code, the buffer is freed twice. The result is undefined behavior: memory may be corrupted, denials of service can occur, and attackers with control over threaded workloads could potentially hijack execution flow.

Conclusion

To remediate, upgrade crossbeam-channel to version 0.5.15 or later. Fedora 41 users should install the updated python-watchfiles package immediately. Red Hat customers should apply the vendor patches for their affected products. Developers of Rust crates and downstream projects should audit their dependencies for the fixed release and update accordingly. That wraps our coverage of CVE-2025-4574—thanks for listening, and stay secure.

Watch the full video on YouTube: CVE-2025-4574

Remediation and exploitation details

This chain involves the following actors

  • Attacker: Exploits the race condition to corrupt memory
  • Rust Developer: Maintains code using crossbeam-channel
  • Fedora 41 User: Runs python-watchfiles built on the vulnerable crate

This following systems are involved

  • crossbeam-channel (Provides thread communication channels): Contains the internal Channel type with a flawed drop method
  • python-watchfiles (Fedora 41) (Monitors file system changes): Bundles the vulnerable crossbeam-channel version
  • Rust Application (Executes user-land code using channels): Host environment for the race-to-free exploit

Attack entry point

  • Channel Drop Method: A race condition in the destructor of the internal Channel type can free the same memory twice.

Remediation actions

Rust Developer
Upgrade the crossbeam-channel dependency to version 0.5.15 or later
crossbeam-channel
Fedora 41 User
Install the patched python-watchfiles package from the security repository
python-watchfiles
Rust Developer
Rebuild and redeploy all affected Rust applications
Rust Application

Exploitation actions

Channel instantiation

Attacker
Create an unbounded channel and share its sender and receiver ends between threads
crossbeam-channel
Examples:
  • let (sender, receiver) = crossbeam_channel::unbounded();

Controlled drop of sender

Attacker
Launch a sender thread that sends a dummy value and then drops its sender handle
crossbeam-channel
Examples:
  • std::thread::spawn(move || {
  • sender.send(42).unwrap();
  • drop(sender);
  • });

Concurrent drop of receiver

Attacker
Simultaneously launch a receiver thread that drops its receiver handle without reading
crossbeam-channel
Examples:
  • std::thread::spawn(move || {
  • drop(receiver);
  • });

Race amplification

Attacker
Repeat spawning these threads in a tight loop to amplify the race window
crossbeam-channel
Examples:
  • for _ in 0..1_000_000 {
  • /* spawn sender and receiver threads */
  • }

Memory corruption observation

Attacker
Detect a crash or error log indicating a double-free
Rust Application
Examples:
  • error: double free detected in runtime

Post-corruption exploitation

Attacker
Use the corrupted memory state to corrupt adjacent data or hijack control flow
Rust Application
Examples:
  • Overwrite vtable pointer or function callback slot

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-4574
Description
In crossbeam-channel rust crate, the internal `Channel` type's `Drop` method has a race condition which could, in some circumstances, lead to a double-free that could result in memory corruption.
Provider
redhat
CWE / problem types
Double Free
Affected Software Versions
None:None:[{'status': 'affected', 'version': '0.5.12', 'lessThan': '0.5.15', 'versionType': 'semver'}],Red Hat:Red Hat Directory Server 11:None,Red Hat:Red Hat Directory Server 12:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 10:None,Red Hat:Red Hat Enterprise Linux 7:None,Red Hat:Red Hat Enterprise Linux 7:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 8:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat Enterprise Linux 9:None,Red Hat:Red Hat OpenShift AI (RHOAI):None,Red Hat:Red Hat OpenShift AI (RHOAI):None,Red Hat:Red Hat OpenShift Container Platform 4:None,Red Hat:Red Hat OpenShift Container Platform 4:None,Red Hat:Red Hat OpenShift Container Platform 4:None,Red Hat:Red Hat OpenShift Container Platform 4:None,Red Hat:Red Hat OpenShift Container Platform 4:None,Red Hat:Red Hat Satellite 6:None,Red Hat:Red Hat Satellite 6:None,Red Hat:Red Hat Trusted Artifact Signer:None,Red Hat:Red Hat Trusted Artifact Signer:None,Red Hat:Red Hat Trusted Profile Analyzer:None
Date Published
2025-05-13T21:47:24.951Z
Last Updated
2025-05-21T18:50:46.684Z