GHSA-WX3M-WHQV-XV47

skillctl: Path traversal and symlink-follow in skillctl allow arbitrary file disclosure and deletion

Credit

Reported privately on 2026-05-19 by firebaguette via the Umanio Discord (the reporter declined GitHub credit, so this advisory carries no structured credits field).

skillctl 0.1.0 and 0.1.1 contained four path-safety vulnerabilities that, in combination, allowed an attacker to:

1. Exfiltrate arbitrary files on the operator's machine by publishing a malicious skills library containing a symlink inside a skill folder (e.g. niania → /home/user/.aws/credentials). The symlink fell through entry.file_type().is_dir() in fs_util::copy_dir_all, was dereferenced by fs::copy, and the target's content was copied into the project. A subsequent skillctl push would have published the secret to the (possibly public) library, what the reporter called "round-trip path exfiltration".

2. Delete arbitrary directories outside the project or library root by crafting a .skills.toml with a malicious destination or source_path field. Both were deserialized as PathBuf with zero validation. Because Path::join lets an absolute right-hand side replace the base, destination = "/home/user/.ssh" made cwd.join(...) resolve outside the project; .. traversal was equally unguarded. Downstream remove_dir_all in replace_folder_contents then wiped arbitrary writable directories on skillctl pull / push / detect. .skills.toml is the exact kind of file teams commit and exchange via PR; a single merged malicious PR was sufficient to weaponise the maintainer's next skillctl pull --all.

3. detect --target accepted .. traversal, even though absolute paths were rejected. --target ../../../etc would have written outside the library root.

4. Fork-name validation accepted . and .. literally, so a fork named .. would have produced a Path::join resolving to the parent directory and fs::rename could have clobbered it.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

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Fixed in v0.1.2:

• Symlinks inside skill folders are hard-rejected at copy time (both top-level source and any descendant entry).
• .skills.toml destination and source_path are validated at load time and reject absolute paths, .. components, and Windows-prefix components.
• A new path_safety::safe_join helper is wired (defense-in-depth) at every destructive call site in pull.rs / push.rs.
• detect --target and the interactive custom-path prompt go through the same validate_relative_subpath helper.
• validate_fork_name explicitly rejects . and ...

Threat-model note: the fix is purely lexical (component-level) plus an explicit symlink check at copy time. No filesystem canonicalize calls were added, avoiding TOCTOU windows.

1. What is GHSA-WX3M-WHQV-XV47? GHSA-WX3M-WHQV-XV47 is a high-severity path traversal vulnerability in skillctl (rust), affecting versions < 0.1.2. It is fixed in 0.1.2. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. Which versions of skillctl are affected by GHSA-WX3M-WHQV-XV47? skillctl (rust) versions < 0.1.2 is affected.
3. Is there a fix for GHSA-WX3M-WHQV-XV47? Yes. GHSA-WX3M-WHQV-XV47 is fixed in 0.1.2. Upgrade to this version or later.
4. Is GHSA-WX3M-WHQV-XV47 exploitable, and should I be worried? Whether GHSA-WX3M-WHQV-XV47 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether GHSA-WX3M-WHQV-XV47 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix GHSA-WX3M-WHQV-XV47? Upgrade skillctl to 0.1.2 or later.

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