CVE-2026-44471

A malicious tree can be constructed that will, when checked out with gitoxide, permit writing an attacker-controlled symlink into any existing directory the user has write access to.

Details

During checkout, all symlink index entries are deferred and created after regular files using a single shared gix_worktree::Stack. Internally, this uses a gix_fs::Stack.

gix_fs::Stack::make_relative_path_current() caches validated path prefixes: when the previously-processed leaf component exactly matches the leading component(s) of the next path, the leaf-to-directory transition at gix-fs/src/stack.rs:195-197 invokes only delegate.push_directory(), never delegate.push().

In gix_worktree::stack::delegate::StackDelegate, when the state member is State::CreateDirectoryAndAttributesStack, Attributes::push_directory() only loads attributes (from the ODB, in the clone case), and does not perform any other checks. The on-disk symlink_metadata() check and unlink-on-collision live in StackDelegate::push()'s invocation of create_leading_directory(), which is therefore bypassed for the cached prefix. The final symlink is created with plain std::os::unix::fs::symlink, which follows symlinks in parent directories.

Therefore, it's possible to provide a tree with duplicate symlink and directory entries that exploits this. If a tree is constructed with:

1. A 120000 (symlink) entry a that points to .git/hooks.
2. A 040000 (directory) entry a with a subtree that contains a symlink from post-checkout to ../../payload.
3. A 100755 (executable file) entry payload.

This is converted by gix_index::State::from_tree() into index entries ["a" (SYMLINK), "a/post-checkout" (SYMLINK)].

Then, during the delayed symlink phase:

1. a is created as a symlink to e.g. .git/hooks.
2. When processing a/post-checkout, the a prefix is reused from the just-processed leaf entry without re-running the intermediate-directory check, after which…
3. symlink(target, "<wt>/a/post-checkout") resolves through the just-created symlink to write .git/hooks/post-checkout.

Although this example uses .git/hooks for simplicity, there's no actual requirement to write within the repo checkout. This can be fairly easily chained into code execution by writing to something that is known to be executed, for example, by writing to .git/hooks/post-checkout if the attacker knows that a hook-aware Git implementation will be used later, or by writing to something like ~/.local/bin.

PoC

Attached is build-bad-repo.sh, which builds a repo with the aforementioned tree structure. Cloning it with gix will set up the malicious .git/hooks/post-checkout, at which point anything that normally invokes the post-checkout hook will result in its execution, such as git checkout -b new-branch.

Disclosure

This vulnerability was found by AI (specifically, Claude Mythos) as part of Project Glasswing. This advisory was written and verified by a human.

Arbitrary symlink creation into any existing directory the user can write to.

CVE-2026-44471 has a CVSS score of 7.8 (High). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.21.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44471? CVE-2026-44471 is a high-severity security vulnerability in gix-fs (rust), affecting versions <= 0.21.0. It is fixed in 0.21.1.
2. How severe is CVE-2026-44471? CVE-2026-44471 has a CVSS score of 7.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of gix-fs are affected by CVE-2026-44471? gix-fs (rust) versions <= 0.21.0 is affected.
4. Is there a fix for CVE-2026-44471? Yes. CVE-2026-44471 is fixed in 0.21.1. Upgrade to this version or later.
5. Is CVE-2026-44471 exploitable, and should I be worried? Whether CVE-2026-44471 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
6. What actually determines whether CVE-2026-44471 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.
7. How do I fix CVE-2026-44471? Upgrade gix-fs to 0.21.1 or later.