CVE-2026-77651: arrayref crate malicious dependency code execution at build time

CVE-2026-77651 · Severity: critical · CVSS 9.8 · Published 2026-08-21

The arrayref Rust library, a widely-used utility crate for array operations, was compromised to include a malicious dependency that downloads and executes arbitrary code during the build process. Developers who built projects using the affected version would unknowingly execute a remote payload, potentially compromising their development machines and entire build environments with arbitrary code execution capabilities.

Technologies: append-only-vec (crates.io), arrayref (crates.io), internment (crates.io), proc-macro1 (crates.io). Vendors: crates.io.

Quick answers

Is CVE-2026-77651 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-77651 being exploited in the wild.
How severe is CVE-2026-77651?
Critical severity, with a CVSS score of 9.8, published 21 August 2026.
Which products and versions are affected?
append-only-vec (crates.io) 0.1.9; arrayref (crates.io) 0.3.10; internment (crates.io) 0.8.7; proc-macro1 (crates.io) 1.0.107.
Is there a fix for CVE-2026-77651?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-77651 attacked?
It is attacked over the network.
Am I affected by CVE-2026-77651?
Check whether you run append-only-vec (crates.io), arrayref (crates.io), internment (crates.io) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A supply chain attack compromised the arrayref crate (v0.3.10) by introducing a malicious dependency on a typosquatted proc-macro1 crate. The attacker's proc-macro1 build script downloads and executes a remote binary from 23.254.165.112:9089, with no certificate validation (AcceptAll verifier). The payload runs during compilation with context-specific executables (Linux: /tmp/rust-setup, Windows: PowerShell via VBS launcher) that spawn detached processes and communicate with a command-and-control server. The attack leverages yanked previous versions (0.3.5–0.3.9) to lure developers to upgrade to the malicious 0.3.10. Patches are not applicable; the malicious versions were deleted from crates.io on 2026-08-20, and the crate maintainer's account was locked.

Affected products

  • Rust arrayref 0.3.10
  • Rust proc-macro1 1.0.107
  • Rust internment 0.8.7
  • Rust append-only-vec 0.1.9

Timeline

  • 2026-08-20: disclosed: Rust Security Response Team notified of proc-macro1 malice; malicious arrayref 0.3.10 published 07:15 UTC
  • 2026-08-20: other: arrayref 0.3.10 deleted after 86 minutes online
  • 2026-08-20: other: append-only-vec 0.1.9 deleted after 107 minutes online
  • 2026-08-21: advisory

References

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