skilo add follows symbolic links, allowing arbitrary local file disclosure from a malicious skill source

Overview

Impact

skilo add installs a skill by recursively copying the skill directory into the target skills directory. The copy routine (copy_dir_all) classified each entry with std::fs::DirEntry::file_type() — which does not follow symlinks — and then copied non-directory entries with std::fs::copy(), which does dereference symlinks.

As a result, a skill containing a symbolic link such as reference.txt -> /home/<user>/.ssh/id_rsa was copied as a regular file whose contents are the link's target. A malicious skill source — for example a git repository installed via skilo add github.com/<attacker>/<skills>, or a local path — could read arbitrary files readable by the user running skilo add (SSH keys, cloud credentials, .env files, etc.) and place their contents inside the installed skill directory, where the user or their agent may later read, share, or sync them.

This is arbitrary local file disclosure (CWE-59 / CWE-61, symlink following) triggered by installing an untrusted skills source.

Patches

Fixed in 0.11.1. copy_dir_all now rejects symbolic-link entries at any recursion depth (failing closed with a dedicated error) instead of dereferencing them.

Workarounds

• Only install skills from sources you trust.
• Inspect a skill source for symbolic links before running skilo add.

Affected versions

Introduced together with the skilo add command in 0.5.0 and present through 0.11.0. Releases before 0.5.0 do not include the add command.

Affected packages

• skilo >= 0.5.0, < 0.11.1

Remediation

Upgrade to a patched release:

• skilo 0.11.1