Rust Security Team Removes Malicious arrayref Republish After Credential Compromise

The Rust Security Response Team disclosed on August 20, 2026 that the arrayref crate — a widely used utility for safe array references — had been republished with a malicious dependency. The incident began with a report at 07:15 UTC that the proc-macro1 crate was malicious. Verification confirmed that its build script downloaded a payload, and the team deleted it along with related crates proc-macro-en, aovine, arone, aronenao, and tinymember.

Further investigation revealed that arrayref had been republished as version 0.3.10 and made to depend on the malicious crate. The team removed that version and unyanked the versions that had been maliciously yanked. Other crates by the same author — internment and append-only-vec — were also affected and received the same treatment. The account has been locked as a precaution.

The team does not believe the author of arrayref acted maliciously. The working theory is that their computer or credentials were compromised. Contact attempts are underway.

Malicious versions and exposure window

• append-only-vec@0.1.9 — published 07:37:49Z, deleted 09:25:24Z (online 107 minutes)
• arrayref@0.3.10 — published 07:15:00Z, deleted 08:41:40Z (online 86 minutes)
• internment@0.8.7 — published 07:34:07Z, deleted 09:04:11Z (online 90 minutes)
• proc-macro1, proc-macro-en, aovine, arone, aronenao, tinymember — all versions deleted

What you need to do

Check your local dependency cache for any of these crates. The team provided a quick find command that scans ~/.cargo/registry/cache for the malicious crate files:

find ~/.cargo/registry/cache -type f \(
  -name 'append-only-vec-0.1.9.crate' -o \
  -name 'arrayref-0.3.10.crate' -o \
  -name 'internment-0.8.7.crate' -o \
  -name 'proc-macro1-*.crate' -o \
  -name 'proc-macro-en-*.crate' -o \
  -name 'aovine-*.crate' -o \
  -name 'arone-*.crate' -o \
  -name 'aronenao-*.crate' -o \
  -name 'tinymember-*.crate' \
\) -print

If any of these appear in your dependency tree, treat them as compromised and rotate any credentials or secrets that could have been exposed. The malicious versions were online for roughly 1.5 to 2 hours, so the exposure window is narrow but real.

The team thanked the Research Team at Nextron Systems GmbH for the initial discovery, along with the individual responders.