GHSA-q54r-jf2p-rfr2

gitoxide gix: untrusted .git/config disables filesystem .git-protection path checks via unfiltered protect_options()

Published

2026-10-23

Modified

2026-10-23

Sources

github-advisory

Summary

## Summary In the `gix` crate, `Cache::protect_options()` in `gix/src/config/cache/access.rs` reads the three filesystem path-protection settings (`core.protectHFS`, `core.protectNTFS`, and `gitoxide.core.protectWindows`) with the unfiltered `gix_config::File::boolean()` accessor instead of the trust-aware `boolean_filter()` accessor used by every other security-critical config read in the same file. When a repository is opened with reduced trust (an ownership mismatch, which maps `.git/config` sections to `Trust::Reduced`), these protection settings should not be honored from the untrusted repository-local config. Because the trust filter is skipped, an attacker who controls a repository's `.git/config` on a shared filesystem can set `core.protectNTFS = false` and/or `core.protectHFS = false`, disabling the `.git` path-confusion checks that run during checkout, index creation, merge, and tree editing. On case-insensitive filesystems this lets crafted tree entries resolve to the `.git` directory and overwrite hooks or config. ## Root Cause Repositories opened under `Trust::Reduced` install a section filter (`is_trusted`) so that security-relevant settings coming from an untrusted repository-local `.git/config` are ignored. The `Cache` struct stores this filter and applies it throughout `gix/src/config/cache/access.rs` for diff drivers, merge drivers, URL rewrites, scheme permissions, lock timeout, and checkout workers. `protect_options()` is the exception: it reads the path-protection booleans through `self.resolved.boolean(...)`, which delegates to `boolean_filter(key, |_| true)` and therefore accepts values from every section regardless of trust. As a result, an untrusted repository-local setting of `core.protectHFS`/`core.protectNTFS`/`gitoxide.core.protectWindows` overrides the safe defaults, defeating the trust boundary for exactly the controls that are meant to prevent `.git` path-confusion attacks. ```text gix/src/config/cache/access.rs:300 Cache::protect_options() : vulnerable function gix/src/config/cache/access.rs:306 self.resolved.boolean(gitoxide.core.protectWindows) (unfiltered) gix/src/config/cache/access.rs:310 self.resolved.boolean(core.protectHFS) (unfiltered) gix/src/config/cache/access.rs:314 self.resolved.boolean(core.protectNTFS) (unfiltered) gix-config/src/file/access/comfort.rs:89 boolean() delegates to boolean_filter(key, |_| true) gix/src/config/mod.rs:61 is_trusted() : the filter that would reject untrusted repo-local sections gix-validate/src/path.rs:98 component() : path validation that honors the resulting options ``` ## Impact An attacker who owns a repository on a filesystem shared with the victim (a multi-user development host, a shared or network-mounted checkout, or a CI workspace reused across jobs) edits that repository's `.git/config` to disable one or both of `core.protectHFS` and `core.protectNTFS`. When the victim opens the repository with a `gix`-based tool, the ownership mismatch yields `Trust::Reduced`, which should neutralize these untrusted settings, but `protect_options()` honors them anyway. The attacker also commits tree entries whose names are filesystem-specific encodings of `.git` (for example NTFS short names such as `GIT~1`, NTFS alternate-data-stream or trailing-dot/space variants, or HFS+ forms using ignorable code points). When the victim performs a checkout, index build, merge, or tree edit, path validation no longer rejects these names, so on a case-insensitive filesystem (Windows NTFS, macOS HFS+) they collapse to the real `.git` directory. This permits overwriting repository hooks and configuration, which plausibly leads to arbitrary command execution in the victim's context on the next Git operation that runs a hook. The confidentiality, integrity, and availability impact follows from control over the victim's `.git` directory and any resulting hook execution; hook execution was not freshly executed here and is characterized as

Affected packages

Remediation: Upgrade to 0.90.0 or later.

References

• https://github.com/advisories/GHSA-q54r-jf2p-rfr2