GHSA-p3hw-mv63-rf9w

Summary

Submodule name validation bypass plus missing validation in production code paths allows path traversal via crafted .gitmodules. Combined with a trust inheritance flaw in Submodule::open(), this enables reading arbitrary git repository configs (including credentials) from traversed paths with full trust (CWE-22, CWE-200).

Details

Bug 1: Validation bypass in gix-validate/src/submodule.rs (lines 27-42)

The name() function uses name.find(b"..") which returns only the FIRST occurrence. If the first .. is embedded in a non-traversal context, the function returns Ok without checking subsequent ../ sequences:

pub fn name(name: &BStr) -> Result<&BStr, name::Error> {
    match name.find(b"..") {
        Some(pos) => {
            let &b = name.get(pos + 2).ok_or(name::Error::ParentComponent)?;
            if b == b'/' || b == b'\\' {
                Err(name::Error::ParentComponent)
            } else {
                Ok(name)  // Returns Ok without checking rest of string
            }
        }
        None => Ok(name),
    }
}

Bypass: a..b/../../../.git/ passes because find(b"..") returns position 1 (the .. in a..b), checks name[3] == b'b', and returns Ok. The real /../../../ is never checked.

Bug 2: Validation never called in production

gix_validate::submodule::name() has zero production callers (only test code). The names() iterator in gix-submodule/src/access.rs:29 explicitly documents it returns "unvalidated names."

git_dir() at gix/src/submodule/mod.rs:198-204 constructs filesystem paths from raw names:

pub fn git_dir(&self) -> PathBuf {
    self.state.repo.common_dir().join("modules").join(gix_path::from_bstr(self.name()))
}

Bug 3: Trust inheritance bypass in Submodule::open()

At gix/src/submodule/mod.rs:270, open() clones the parent repository's options:

match crate::open_opts(self.git_dir_try_old_form()?, self.state.repo.options.clone()) {
```...