AIKIDO-2026-269507
event-listener is vulnerable to Race Condition
40
CVE Score
Medium
Race Condition
TL;DR
Affected versions of event-listener unconditionally implement Send and Sync for StackSlot<'_, T>, the stack-allocated listener type created by the listener! macro. That lets a !Send tag set via Event::with_tag be moved to another thread and accessed through StackSlot::wait, causing a data race in safe Rust. The fix adds a T: Send bound on the Send/Sync implementations for StackSlot.
How do I fix this?
Upgrade the event-listener library to the patch version.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and create an Event with Event::with_tag using a !Send tag type, then move a listener!-created StackSlot across threads.
Package
Versions
5.1.0 - 5.4.1
Fixed in 5.4.2Background info
event-listener is vulnerable to Race Condition in versions 5.1.0 - 5.4.1.
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