CVE-2025-4574 Overview
CVE-2025-4574 is a double-free vulnerability [CWE-415] in the crossbeam-channel Rust crate, a widely used library for multi-producer multi-consumer channel communication in concurrent Rust programs. The flaw resides in the Drop implementation of the internal Channel type, where a race condition between threads can cause the same memory to be freed twice. Under specific conditions, this double-free leads to memory corruption in affected applications. The issue is tracked as GitHub Security Advisory GHSA-pg9f-39pc-qf8g and was addressed via crossbeam pull request #1187.
Critical Impact
A concurrency bug in the Channel::drop path can produce a double-free, corrupting the heap of any Rust process linking a vulnerable version of crossbeam-channel.
Affected Products
- crossbeam-channel Rust crate (versions prior to the fix in PR #1187)
- Rust applications and libraries transitively depending on vulnerable crossbeam-channel releases
- Red Hat products bundling the affected crate, per the Red Hat CVE-2025-4574 advisory
Discovery Timeline
- 2025-05-13 - CVE-2025-4574 published to NVD
- 2026-06-30 - Last updated in NVD database
Technical Details for CVE-2025-4574
Vulnerability Analysis
The defect is a classic double-free triggered by a race condition in the crate's Channel teardown logic. When multiple threads drop references to the same underlying channel concurrently, the Drop implementation can execute the deallocation path more than once for a single allocation. The result is heap metadata corruption, which can manifest as process crashes, allocator invariant violations, or exploitable memory state. Because the vulnerability is in the concurrency primitives themselves, Rust's compile-time safety guarantees do not prevent it — the unsafe deallocation logic bypasses the borrow checker.
Root Cause
The root cause is inadequate synchronization in the Channel type's Drop method. Reference-count decrement and the subsequent deallocation are not performed atomically with respect to concurrent drops. Two threads can each observe a state that leads them to release the underlying channel storage, causing the same allocation to be freed twice. This maps to [CWE-415: Double Free].
Attack Vector
Exploitation requires the attacker to influence timing or workload of a target process that uses vulnerable crossbeam-channel code paths. In server contexts that accept network input and dispatch work across channels, remote attackers can potentially provoke the race by driving concurrent channel drops. Successful triggering causes memory corruption, with likely outcomes of denial of service through process crash and, in worst cases, undefined behavior that undermines integrity of adjacent heap data.
No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Red Hat Bugzilla entry #2358890 for additional technical context.
Detection Methods for CVE-2025-4574
Indicators of Compromise
- Unexpected process crashes or SIGABRT in Rust services referencing crossbeam-channel frames on the stack.
- Allocator diagnostics reporting double-free, corrupted malloc metadata, or invalid pointers during Channel::drop.
- AddressSanitizer or Valgrind reports flagging duplicate free calls originating in crossbeam_channel::channel internals.
Detection Strategies
- Inventory Rust binaries and container images to identify direct and transitive dependencies on crossbeam-channel using cargo tree or cargo audit.
- Run cargo audit against project lockfiles to match advisory GHSA-pg9f-39pc-qf8g.
- Enable AddressSanitizer builds for critical Rust services in CI to surface double-free conditions before deployment.
Monitoring Recommendations
- Alert on abnormal crash rates or core dumps for production Rust workloads, correlating with recent traffic patterns.
- Ingest allocator error output and OS-level crash telemetry into your SIEM or data lake for anomaly detection.
- Track supply-chain advisories for Rust crates as part of vulnerability management workflows.
How to Mitigate CVE-2025-4574
Immediate Actions Required
- Upgrade crossbeam-channel to a patched release incorporating the fix from crossbeam PR #1187 and rebuild all dependent artifacts.
- Regenerate Cargo.lock files and rebuild container images to ensure no vulnerable version is pulled transitively.
- Consult the Red Hat CVE-2025-4574 advisory for distribution-specific package updates.
Patch Information
The upstream fix is merged in the crossbeam-rs/crossbeam repository via pull request #1187, which corrects the synchronization in the Channel type's Drop implementation. Downstream distributions such as Red Hat are shipping updated packages tracked under Bugzilla #2358890. Consumers should update to the fixed crate version referenced in advisory GHSA-pg9f-39pc-qf8g.
Workarounds
- No supported workaround exists at the source level; upgrading the crate is the required remediation.
- Reduce exposure by limiting untrusted concurrent workloads on services that cannot immediately be rebuilt.
- Enable allocator hardening features (for example, MALLOC_CHECK_ on glibc) to fail fast on corruption while patching is in progress.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
