internment (Rust crate) EUVD-2026-63778

Exploitation requires that a Rust project's dependency graph resolve internment at exactly version 0.8.7 and that the project then be compiled (cargo build/test/CI), because the payload lives in the crate's build/dependency execution path and fires at compile time, not runtime. Concrete prerequisites: the crate must be present as a direct or transitive dependency, the toolchain must fetch it from crates.io (not overridden by a vendored/patched copy), and the build host must have outbound network access for the C2 registration to succeed. Limiting factors that reduce real-world exposure: only the single 0.8.7 release is malicious (any other pinned version is unaffected), a human or pipeline must actually build the project, offline or egress-restricted build environments blunt the C2 callback, and the input contains no KEV/EPSS/POC evidence indicating broad automated exploitation - impact is confined to those who specifically pulled this version.

The input CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H = 9.8) treats this as fully remote and unauthenticated, but that scoring understates the required precondition: a developer or CI pipeline must add and compile a project that resolves internment 0.8.7, which is best modeled as user interaction (UI:R). The impact is nonetheless real - arbitrary code execution on build infrastructure, which is high-value and often holds signing keys, cloud credentials, and source access. No EPSS score, no CISA KEV entry, and no public POC are provided, so quantitative exploitation-probability signals are absent; however, this is confirmed malicious code by construction, so the practical risk to anyone who actually pulled 0.8.7 is severe. The realistic risk is therefore bimodal: negligible for the majority who never depended on this crate at this exact version, and critical for the specific victims who did. Missing data to note: no SSVC decision, no EPSS, and KEV status not present in the input - do not treat absence of KEV as evidence the payload was never delivered.

A developer adds internment as a dependency (or updates a lockfile) such that version 0.8.7 is resolved, then runs cargo build or triggers a CI pipeline. During compilation the rogue transitive dependency executes, contacts the attacker's command-and-control server, and runs arbitrary commands on the build host - for example dumping environment secrets and CI tokens or implanting a backdoor. No separate public exploit is needed because the malicious code is itself the payload; the only requirement is that the poisoned version enters the build.