Hydra legacy target blacklist permits unsafe PyYAML loading

{
  "id": "1072e9379af0dbf24ba6f3ee7785bf077f6838e5cdbf25065da53672bd6c9825",
  "url": "https://osv.dev/vulnerability/GHSA-wf6j-7hvr-gr93",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Hydra legacy target blacklist permits unsafe PyYAML loading",
    "summary": "## Summary Hydra's legacy target blacklist omits PyYAML's unsafe loading surfaces. If an application passes attacker-controlled targets and arguments to instantiate(), a target such as yaml.unsafe_load can execute Python code through a config-controlled YAML stream containing Python object-construction tags. ## Impact and prerequisites The attacker must control the relevant target and arguments that the application instantiates. The configured callable executes with the application's process privileges. This is a gap in the best-effort legacy blacklist. It is not a bypass of Hydra 1.4's execution whitelist supplied by trusted Python code. One realistic exposure is a model downloaded from a third-party repository, such as Hugging Face, that bundles attacker-controlled configuration. When a victim loads the model using application code that passes this configuration to legacy Hydra instantiation without effective target restrictions, the model's metadata can execute code in the victim process. This model-loading attack pattern is documented in the original Hydra advisory GHSA-2cp2-2r3c-7p7r and the associated Unit 42 research. It does not imply that all Hugging Face models or currently patched downstream loaders are affected. Hydra 1.3's blacklist is defense in depth, not a complete security boundary. Hydra 1.4 is affected on its deprecated no-whitelist legacy path. Installed application wrappers can perform indirect operations beyond a name-based blacklist's coverage; this fix",
    "evidence": "osv:GHSA-wf6j-7hvr-gr93",
    "products": [
      {
        "name": {
          "value": "hydra-core",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.3.8",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.3.6",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.3.7",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "hydra-core",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.4.0rc3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.4.0.dev10",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.4.0.dev9",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.4.0rc1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.4.0rc2",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-wf6j-7hvr-gr93",
      "aliases": [
        "GHSA-wf6j-7hvr-gr93"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "1.3.6"
                },
                {
                  "fixed": "1.3.8"
                }
              ]
            }
          ],
          "package": {
            "name": "hydra-core",
            "purl": "pkg:pypi/hydra-core",
            "ecosystem": "PyPI"
          },
          "versions": [
            "1.3.6",
            "1.3.7"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-wf6j-7hvr-gr93/GHSA-wf6j-7hvr-gr93.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "1.4.0.dev9"
                },
                {
                  "fixed": "1.4.0rc3"
                }
              ]
            }
          ],
          "package": {
            "name": "hydra-core",
            "purl": "pkg:pypi/hydra-core",
            "ecosystem": "PyPI"
          },
          "versions": [
            "1.4.0.dev10",
            "1.4.0.dev9",
            "1.4.0rc1",
            "1.4.0rc2"
          ],
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-wf6j-7hvr-gr93/GHSA-wf6j-7hvr-gr93.json"
          }
        }
      ],
      "modified": "2026-10-27T17:15:04.232998356Z",
      "provider": "osv",
      "references": [
        "https://github.com/hydra-ecosystem/hydra/security/advisories/GHSA-757g-8w3h-hp29",
        "https://github.com/hydra-ecosystem/hydra/commit/9a7a9a287d565311183da3392bee4345a7fab6d7",
        "https://github.com/hydra-ecosystem/hydra/commit/de5554320c17cd2d974492c03d0b1456adb4a8ef",
        "https://github.com/hydra-ecosystem/hydra",
        "https://github.com/hydra-ecosystem/hydra/releases/tag/v1.3.8",
        "https://github.com/hydra-ecosystem/hydra/releases/tag/v1.4.0rc3"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-184"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-27T17:08:41Z"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 462902,
  "published_at": "2026-10-27T17:08:41+00:00"
}