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Fencer Intel
no cvss —

RUSTSEC-2026-0265 json

`proc-macro1` was removed from crates.io due to malicious code

published 2mo ago modified 2mo ago

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
—
no score, EPSS covers CVEs only
public exploits
0
none known

Summary

It was reported `proc-macro1` contained a build script that would download a malicious payload.

This crate had two versions, both published on 2026-08-20. The crate was removed from crates.io and related user accounts were locked.

This crate was used as part of a malware campaign targeted at users of `arrayref`, which was downloaded 2,285 times before being removed; see [the `arrayref` advisory][arrayref-advisory] for more detail.

Thanks to the Research Team at Nextron Systems GmbH for reporting this to the Rust security response working group, and thanks to Emily Albini for coordinating with the crates.io and infra-admin teams.

[arrayref-advisory]: https://rustsec.org/advisories/RUSTSEC-2026-0260.html

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Affected packages

ecosystem package affected fixed in
crates.io proc-macro1
>=0.0.0-0
 no fix listed

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.