MAL-2026-14339 Malicious code in proc_macro_en (crates.io)
Malicious package
Published
MAL-2026-14339 is a malicious package: proc-macro-en (crates.io). Every version was published to cause harm.
Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.
Reference: https://insights.sbomify.com/MAL-2026-14339/ (Markdown: https://insights.sbomify.com/MAL-2026-14339/index.md)
- Package
- proc-macro-en
- Registry
- crates.io
What is MAL-2026-14339?
MAL-2026-14339 is a malicious package in proc-macro-en, published on 20 Aug 2026.
Official description
proc-macro-en is a malicious crate published to crates.io as part of the coordinated build-time payload campaign on 2026-08-20 that trojanized arrayref, internment, and append-only-vec and published the proc-macro1 typosquat of proc-macro2. It was used as an attacker-controlled dependency carrying a build-script payload; building it results in the download and execution of a remote binary from https://23.254.165.112:9089/ with 23.254.165.112:443 as command and control. All versions have been removed from crates.io. The individual build script of this crate was not analyzed directly; its behavior is attributed from the campaign.
What should I do about MAL-2026-14339?
Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.