SHA-1 collision attacks are not detected

{
  "id": "ef20bc9b02e8bd811de85b72d12864406582ed5b0d33b0f37a4e84307d24ffcd",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2025-0021",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SHA-1 collision attacks are not detected",
    "summary": "### 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 { // Matches Git’s behaviour. let mut hasher = sha1_checked::Builder::default().safe_hash(false).build(); hasher.update(&std::fs::read(filename",
    "evidence": "osv:RUSTSEC-2025-0021",
    "products": [
      {
        "name": {
          "value": "gix-features",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.41.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "RUSTSEC-2025-0021",
      "aliases": [
        "CVE-2025-31130",
        "GHSA-2frx-2596-x5r6",
        "RUSTSEC-2025-0021"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.41.0"
                }
              ]
            }
          ],
          "package": {
            "name": "gix-features",
            "purl": "pkg:cargo/gix-features",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2025-0021.json",
            "categories": [
              "crypto-failure"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": [
                "gix_features::hash::Hasher::digest",
                "gix_features::hash::Hasher::update",
                "gix_features::hash::Write::flush",
                "gix_features::hash::Write::new",
                "gix_features::hash::Write::write",
                "gix_features::hash::bytes",
                "gix_features::hash::bytes_of_file",
                "gix_features::hash::bytes_with_hasher",
                "gix_features::hash::hasher"
              ]
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:10.946699881Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/gix-features",
        "https://rustsec.org/advisories/RUSTSEC-2025-0021.html",
        "https://github.com/GitoxideLabs/gitoxide/commit/f253f02a6658b3b7612a50d56c71f5ae4da4ca21",
        "https://github.com/advisories/GHSA-2frx-2596-x5r6",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-31130"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-31130",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306409,
  "published_at": "2025-04-03T12:00:00+00:00"
}