jdx/mise · critical

brew-cask: staged symlink path escaped extraction root

Error message

brew-cask: staged symlink path escaped extraction root: {}

What it means

While copying the staged tree into mise's private caskroom (src/system/packages/brew/cask.rs:1688), every path must resolve inside the extraction root. If staged_relative_path cannot express a source relative to the stage, or the source's parent is not under the resolved stage root, the payload contains a symlink that escapes the extraction directory, and mise refuses to follow it.

Solutions

Inspect the cask's payload yourself: download the cask URL, extract it, and run `find . -type l -ls` to see the escaping symlink
Treat this as a security boundary, not a bug — do not install casks from taps you do not trust
Prefer the official homebrew/cask build of the app
Report the offending cask to the tap maintainer

Defensive patterns

Strategy: validation

Validate before calling

# reject escaping symlinks before install
find "$EXTRACT_DIR" -type l -printf '%p -> %l' | grep -E '\.\.|^/' && { echo 'escaping symlink'; exit 1; }

Prevention

Only install casks from taps you trust — the escape check is a security boundary
Scan extracted archives in CI for absolute or ../ symlinks before republishing them as casks
Treat any hit of this error as a supply-chain incident, not a bug to work around

When it happens

Trigger: An extracted cask archive containing absolute symlinks or links traversing '../../..' out of the extraction directory, so an installed artifact would point outside the staged tree — the classic hostile-payload shape this guard exists for.

Common situations: Malicious or repackaged third-party casks; archives built with unusual tooling that symlink to /tmp or system locations; taps whose artifacts were re-packed after tampering.

Understand the failure class

Background: Path traversal blocked: "path escapes the workspace" and "outside site root" errors when a path will not stay inside its allowed directory — this error's family across 26 libraries.

Related errors

AI-assisted analysis of jdx/mise@6f52dcdf99 (2026-08-22). Data as JSON: /api/errors/76c67b62f58702ae. Report an issue: GitHub.

Appendix: source

Thrown at src/system/packages/brew/cask.rs:1688

}

fn copy_staged_artifact_closure(stage: &Path, owned_stage: &Path, source: &Path) -> Result<()> {
    let stage = lexically_normalized_path(stage);
    let mut pending = vec![lexically_normalized_path(source)];
    let mut visited = BTreeSet::new();
    while let Some(source) = pending.pop() {
        let relative = staged_relative_path(&stage, &source).ok_or_else(|| {
            eyre!(
                "brew-cask: staged symlink target escaped extraction root: {}",
                source.display()
            )
        })?;
        if relative.components().next().is_some()
            && !source
                .parent()
                .is_some_and(|parent| path_starts_with_resolved_root(parent, &stage))
        {
            bail!(
                "brew-cask: staged symlink path escaped extraction root: {}",
                source.display()
            );
        }
        if !visited.insert(relative.to_path_buf()) {
            continue;
        }
        let destination = owned_stage.join(&relative);
        let metadata = source.symlink_metadata()?;
        if destination.symlink_metadata().is_err() {
            if let Some(parent) = destination.parent() {
                file::create_dir_all(parent)?;
            }
            if metadata.file_type().is_symlink() {
                file::make_symlink(&std::fs::read_link(&source)?, &destination)?;
            } else {
                copy_cask_artifact(&source, &destination)?;
            }

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