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The vulnerability in `crossbeam-channel` arises due to a race condition in the `Drop` implementation of the internal `Channel` type. When multiple threads attempt to drop the same channel simultaneously, improper synchronization can lead to a double-free scenario. This occurs because the destructor fails to handle concurrent access safely, allowing two threads to free the same memory region. Memory corruption or arbitrary code execution could result if an attacker manipulates this flaw.
The issue stems from Rust’s lack of automatic thread-safe `Drop` guarantees. While `crossbeam-channel` is designed for concurrent use, the `Drop` trait implementation did not enforce proper locking mechanisms. When a channel is dropped, its internal buffers are deallocated. If two threads trigger the `Drop` sequence concurrently, both may attempt to free the same resources, corrupting the heap.
DailyCVE Form:
Platform: Rust
Version: crossbeam-channel < 0.5.5
Vulnerability: Double Free
Severity: Moderate
Date: May 14, 2025
What Undercode Say:
Exploitation:
- Trigger concurrent drops by spawning multiple threads sharing the same channel.
- Force rapid channel destruction under high load to exploit the race condition.
3. Craft malicious payloads to manipulate freed memory.
Protection:
1. Upgrade to `crossbeam-channel >= 0.5.5`.
2. Avoid shared channel ownership across threads.
3. Use `Arc>` for manual drop control.
Analytics:
- CVSS Score: 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- Affected Versions: All releases before 0.5.5.
Commands:
cargo update -p crossbeam-channel --precise 0.5.5
Code Snippet (Vulnerable Drop):
impl Drop for Channel {
fn drop(&mut self) {
unsafe { dealloc(self.buffer); } // Race condition here
}
}
Patch Code:
impl Drop for Channel {
fn drop(&mut self) {
let lock = self.lock.acquire(); // Thread-safe drop
unsafe { dealloc(self.buffer); }
}
}
Detection Script:
cargo audit | grep "crossbeam-channel"
Mitigation Workaround:
let channel = Arc::new(Mutex::new(Channel::new())); // Manual synchronization
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
