{"items":[{"id":"NVI-00013143","kind":"vulnerability","title":"NLTK downloader allows cross-package resource and model poisoning","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-ffj6-66c4-86gw","CVE-2026-12261"],"plain_summary":"GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-723964a894ab655579882b7b17bdbfbe"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-10-02T23:09:22.000Z","value":"5.3 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-723964a894ab655579882b7b17bdbfbe"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-723964a894ab655579882b7b17bdbfbe","url":"https://github.com/advisories/GHSA-ffj6-66c4-86gw","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-ffj6-66c4-86gw","publisher":"GitHub Advisory Database","observed_at":"2026-11-01T01:40:00.567Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-723964a894ab655579882b7b17bdbfbe"],"technology":"nltk","known_exclusions":[],"conditions_summary":"A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has been written and extracted. This design flaw enables one package to overwrite another package's trusted resources within the same namespace, making the changes immediately active through ordinary NLTK APIs. This issue persists across fresh interpreter restarts and can affect downstream workflows, including machine learning pipelines and reproducibility-sensitive environments.","public_affected_ranges":["< 3.10.0"]}],"null_published_at":"2026-11-01T07:29:12.925Z","source_updated_at":"2026-10-02T23:09:22.000Z","source_disclosed_at":"2026-08-07T09:31:52.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-01T01:40:00.567Z"}],"next_cursor":null,"snapshot_revision":"42594"}