`tracing_checks` was removed from crates.io for transitively including malicious code

Summary

This is part of an ongoing campaign to attempt to typosquat crates in an attempt to exfiltrate Polymarket credentials.

The malicious crate had 1 version published on 2026-02-26 approximately 9 hours before removal and had no evidence of actual usage, both in terms of downloads and dependents. It did not include the malware payload itself; this was instead delivered via the `tracings` crate, which has received a separate advisory.

Thanks to Marko Ćupić for finding and reporting this to the Rust security response working group, and to Emily Albini for co-ordinating with the crates.io team.

The crates.io team advises anyone developing with Polymarket to review dependencies carefully. We are investigating ways to mitigate this attacker who appears to be very motivated to steal Polymarket credentials.