{"items":[{"id":"NVI-00015164","kind":"vulnerability","title":"h2: Duplicate Host header could facilitate request smuggling","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-6hr6-w5qg-qmwg","CVE-2026-71554"],"plain_summary":"GitHub lists this reviewed advisory for h2. 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-340957e2a7aa554319388f9c191c84da"],"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":"2026-08-06T21:53:43.000Z","value":"5.3 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-340957e2a7aa554319388f9c191c84da"}],"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-340957e2a7aa554319388f9c191c84da","url":"https://github.com/advisories/GHSA-6hr6-w5qg-qmwg","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-6hr6-w5qg-qmwg","publisher":"GitHub Advisory Database","observed_at":"2026-11-03T02:28:46.523Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-340957e2a7aa554319388f9c191c84da"],"technology":"h2","known_exclusions":[],"conditions_summary":"### Impact\nh2 <=4.4.0 accepts request header blocks containing more than one Host header, and forwards every Host header to the consuming application. Where the consumer downgrades HTTP/2 to HTTP/1.1, the resulting request carries two Host header lines, which is a request smuggling primitive (CWE-444).\n\n### Patches\nPatched and fixed in v4.4.1\n\n### Workarounds\nUsers of the h2 library are advised to check and follow HTTP semantics best practices in their application code. h2 provides best effort sanity checks, but ultimately the calling code is responsible to ensure proper and safe usage of HTTP/2 as provided by h2, hyperframe, and hpack.\n\n### References\nSimilar to the previously disclosed and fixed duplicate content-length issue.","public_affected_ranges":["<= 4.4.0"]}],"null_published_at":"2026-11-03T10:03:26.555Z","source_updated_at":"2026-08-06T21:53:43.000Z","source_disclosed_at":"2026-08-06T21:53:41.000Z","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":"2026-11-03T02:28:46.523Z"}],"next_cursor":null,"snapshot_revision":"42594"}