{"id":"GHSA-wx3m-whqv-xv47","summary":"skillctl: Path traversal and symlink-follow in skillctl allow arbitrary file disclosure and deletion","details":"## Impact\n\n`skillctl` 0.1.0 and 0.1.1 contained four path-safety vulnerabilities that, in combination, allowed an attacker to:\n\n1. **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\".\n\n2. **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`.\n\n3. **`detect --target` accepted `..` traversal**, even though absolute paths were rejected. `--target ../../../etc` would have written outside the library root.\n\n4. **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.\n\n## Patches\n\nFixed in [v0.1.2](https://github.com/umanio-agency/skillctl/releases/tag/v0.1.2):\n\n- Symlinks inside skill folders are hard-rejected at copy time (both top-level source and any descendant entry).\n- `.skills.toml` `destination` and `source_path` are validated at load time and reject absolute paths, `..` components, and Windows-prefix components.\n- A new `path_safety::safe_join` helper is wired (defense-in-depth) at every destructive call site in `pull.rs` / `push.rs`.\n- `detect --target` and the interactive custom-path prompt go through the same `validate_relative_subpath` helper.\n- `validate_fork_name` explicitly rejects `.` and `..`.\n\nThreat-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.\n\n## Credit\n\nReported privately on 2026-05-19 by **firebaguette** via the Umanio Discord (the reporter declined GitHub credit, so this advisory carries no structured credits field).","modified":"2026-06-19T05:15:08.472072586Z","published":"2026-06-05T19:43:51Z","database_specific":{"github_reviewed_at":"2026-06-05T19:43:51Z","nvd_published_at":null,"cwe_ids":["CWE-22","CWE-61"],"severity":"HIGH","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/umanio-agency/skillctl/security/advisories/GHSA-wx3m-whqv-xv47"},{"type":"WEB","url":"https://github.com/umanio-agency/skillctl/commit/827fff5c0698dd9e48e777d5907cf7bc19b91aca"},{"type":"PACKAGE","url":"https://github.com/umanio-agency/skillctl"},{"type":"WEB","url":"https://github.com/umanio-agency/skillctl/releases/tag/v0.1.2"}],"affected":[{"package":{"name":"skillctl","ecosystem":"crates.io","purl":"pkg:cargo/skillctl"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.1.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-wx3m-whqv-xv47/GHSA-wx3m-whqv-xv47.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N"}]}