gitoxide before 0.52.1 fails to validate submodule names from .gitmodules configuration, allowing path traversal when deriving submodule git directories. Attackers can craft malicious submodule names with traversal segments to redirect state() and open() functions to repositories outside .git/modules, causing repository confusion and inspection of attacker-controlled repositories.

gitoxide before 0.52.1 follows symlinks when reading the worktree .gitmodules file, allowing attackers to inject out-of-repository bytes into submodule metadata. Attackers can create a malicious repository with a symlinked .gitmodules pointing outside the repository tree, causing gitoxide to parse arbitrary external files as submodule configuration and expose attacker-controlled name, path, and url values.

gitoxide before 0.38.2 fails to validate carriage return characters in URL values passed to credential helpers. Attackers can supply URLs containing bare carriage returns to inject additional helper protocol fields and cause credential helpers to return credentials for attacker-specified hosts instead of the requested URL.

gix-worktree-state before 0.33.0 (part of gitoxide) allows writing files outside the worktree on Windows. gixworktreestate::checkout() follows an existing terminal symlink during non-exclusive (incremental) materialization (destinationisinitiallyempty: false) when core.symlinks is true. If a symlink entry (mode 120000) is first checked out at a path P pointing outside the worktree, a subsequent incremental checkout of a regular-file entry (mode 100644) at the same path follows the existing reparse point and writes the blob content through the link, overwriting files outside the worktree.

Summary gitoxide uses SHA-1 hash implementations without any collision detection, leaving it vulnerable to hash collision attacks.

Details gitoxide uses the sha1smol or sha1 crate, both of which implement standard SHA-1 without any mitigations for collision attacks. This means that two distinct Git objects with colliding SHA-1 hashes would break the Git object model and integrity checks when used with gitoxide.

The SHA-1 function is considered cryptographically insecure. However, in the wake of the SHAttered attacks, this issue was mitigated in Git 2.13.0 in 2017 by using the sha1collisiondetection algorithm by default and producing an error when known SHA-1 collisions are detected. Git is in the process of migrating to using SHA-256 for object hashes, but this has not been rolled out widely yet and gitoxide does not support SHA-256 object hashes.

PoC The following program demonstrates the problem, using the two SHAttered PDFs:

rust use sha1checked::{CollisionResult, Digest};

fn sha1oidoffile(filename: &str) -> gix::ObjectId { let mut hasher = gix::features::hash::hasher(gix::hash::Kind::Sha1); hasher.update(&std::fs::read(filename).unwrap()); gix::ObjectId::Sha1(hasher.digest()) }

fn sha1dcoidoffile(filename: &str) -> Result<gix::ObjectId, String> { // Matches Git’s behaviour. let mut hasher = sha1checked::Builder::default().safehash(false).build(); hasher.update(&std::fs::read(filename).unwrap()); match hasher.tryfinalize() { CollisionResult::Ok(digest) => Ok(gix::ObjectId::Sha1(digest.into())), CollisionResult::Mitigated() => unreachable!(), CollisionResult::Collision(digest) => Err(format!( "Collision attack: {}", gix::ObjectId::Sha1(digest.into()).tohex() )), } }

fn main() { dbg!(sha1oidoffile("shattered-1.pdf")); dbg!(sha1oidoffile("shattered-2.pdf")); dbg!(sha1dcoidoffile("shattered-1.pdf")); dbg!(sha1dcoidoffile("shattered-2.pdf")); }

The output is as follows:

[src/main.rs:24:5] sha1oidoffile("shattered-1.pdf") = Sha1(38762cf7f55934b34d179ae6a4c80cadccbb7f0a) [src/main.rs:25:5] sha1oidoffile("shattered-2.pdf") = Sha1(38762cf7f55934b34d179ae6a4c80cadccbb7f0a) [src/main.rs:26:5] sha1dcoidoffile("shattered-1.pdf") = Err( "Collision attack: 38762cf7f55934b34d179ae6a4c80cadccbb7f0a", ) [src/main.rs:27:5] sha1dcoidoffile("shattered-2.pdf") = Err( "Collision attack: 38762cf7f55934b34d179ae6a4c80cadccbb7f0a", )

The latter behaviour matches Git.

Since the SHAttered PDFs are not in a valid format for Git objects, a direct proof‐of‐concept using higher‐level APIs cannot be immediately demonstrated without significant computational resources.

Impact An attacker with the ability to mount a collision attack on SHA-1 like the SHAttered or SHA-1 is a Shambles attacks could create two distinct Git objects with the same hash. This is becoming increasingly affordable for well‐resourced attackers, with the Shambles researchers in 2020 estimating $45k for a chosen‐prefix collision or $11k for a classical collision, and projecting less than $10k for a chosen‐prefix collision by 2025. The result could be used to disguise malicious repository contents, or potentially exploit assumptions in the logic of programs using gitoxide to cause further vulnerabilities.

This vulnerability affects any user of gitoxide, including gix- library crates, that reads or writes Git objects.