gitoxide is an implementation of git written in Rust. Before 0.42.0, gitoxide uses SHA-1 hash implementations without any collision detection, leaving it vulnerable to hash collision attacks. gitoxide uses the sha1_smol 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. This vulnerability is fixed in 0.42.0.

Affected: crates.io: gix-features, crates.io: gix-commitgraph, crates.io: gix-index, crates.io: gix-object, crates.io: gix-odb, crates.io: gix-pack, crates.io: gitoxide, crates.io: gitoxide-core, crates.io: gix, crates.io: gix-archive and 17 more

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

### Details gitoxide uses the `sha1_smol` 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](https://github.com/crmarcstevens/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](https://shattered.io/):

```rust use sha1_checked::{CollisionResult, Digest};

fn sha1_oid_of_file(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 sha1dc_oid_of_file(filename: &str) -> Result<gix::ObjectId, String> { // Matches Git’s behaviour. let mut hasher = sha1_checked::Builder::default().safe_hash(fal…

gitoxide-0.42.0-1.1 on GA media

Affected: crates.io: gix-features

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

### Details gitoxide uses the `sha1_smol` 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](https://github.com/crmarcstevens/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](https://shattered.io/):

```rust use sha1_checked::{CollisionResult, Digest};

fn sha1_oid_of_file(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 sha1dc_oid_of_file(filename: &str) -> Result<gix::ObjectId, String> { // Matches Git’s behaviour. let mut hasher = sha1_checked::Builder::default().safe_hash(fal…

Affected: Ubuntu:24.04:LTS: rust-gix-features, Ubuntu:25.10: rust-gix-features, Ubuntu:26.04:LTS: rust-gix-features

gitoxide is an implementation of git written in Rust. Before 0.42.0, gitoxide uses SHA-1 hash implementations without any collision detection, leaving it vulnerable to hash collision attacks. gitoxide uses the sha1_smol 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. This vulnerability is fixed in 0.42.0.