{"items":[{"id":"NVI-00018535","kind":"vulnerability","title":"PyJWT: Algorithm allow-list bypass when decoding with `PyJWK` / `PyJWKClient` keys","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-jq35-7prp-9v3f","CVE-2026-48523"],"plain_summary":"GitHub lists this reviewed advisory for pyjwt. 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-3835e8132f17e473d166e47012d488a1"],"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":"2026-06-15T19:27:48.000Z","value":"5.4 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-3835e8132f17e473d166e47012d488a1"}],"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-3835e8132f17e473d166e47012d488a1","url":"https://github.com/advisories/GHSA-jq35-7prp-9v3f","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-jq35-7prp-9v3f","publisher":"GitHub Advisory Database","observed_at":"2026-11-06T15:12:54.193Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-3835e8132f17e473d166e47012d488a1"],"technology":"pyjwt","known_exclusions":[],"conditions_summary":"> [!NOTE]\n> Scored assuming a deployment where algorithm policy functions as an authentication/authorization boundary. In deployments where the algorithm policy enforces crypto agility only, the practical confidentiality impact is lower and the issue is closer to an integrity-of-policy-enforcement bug.\n\nPyJWT `2.9.0` through `2.12.1` allows a verifier-side algorithm allow-list bypass when `jwt.decode()` or `jwt.decode_complete()` are called with a `PyJWK` key. The token header `alg` is checked against the caller-supplied `algorithms` allow-list, but signature verification is performed with the algorithm bound to the `PyJWK` object instead of the header algorithm. An attacker who controls a registered JWK/JWKS private key can sign with a disallowed algorithm, advertise an allowed algorithm in the JWT header, and still be accepted. The issue affects the documented `PyJWKClient.get_signing_key_from_jwt(...)` flow.\n\n### Summary\n\nPyJWT's `PyJWK` verification path allows a verifier-side algorithm allow-list bypass.\n\nIn affected versions, when a JWT is decoded with a `PyJWK` object, PyJWT verifies that the header `alg` string is present in the caller's `algorithms=[...]` list, but it does","public_affected_ranges":[">= 2.9.0, < 2.13.0"]}],"null_published_at":"2026-11-07T07:07:39.849Z","source_updated_at":"2026-06-15T19:27:48.000Z","source_disclosed_at":"2026-06-15T19:27:48.000Z","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":"2026-11-06T15:12:54.193Z"}],"next_cursor":null,"snapshot_revision":"42594"}