{"items":[{"id":"NVI-00008903","kind":"vulnerability","title":"rustls: ECH rejection can expose buffered application data to authenticated outer server before `ech_required` alert","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-vp88-798v-h67f"],"plain_summary":"GitHub lists this reviewed advisory for rustls, rustls. 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-26cf71beee5bbb65749338efe0f52eee"],"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":"2026-10-27T16:09:02.000Z","value":"2.3 low","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-26cf71beee5bbb65749338efe0f52eee"}],"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-26cf71beee5bbb65749338efe0f52eee","url":"https://github.com/advisories/GHSA-vp88-798v-h67f","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-vp88-798v-h67f","publisher":"GitHub Advisory Database","observed_at":"2026-10-31T21:56:51.534Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-26cf71beee5bbb65749338efe0f52eee"],"technology":"rustls","known_exclusions":[],"conditions_summary":"In rustls 0.23.44 and 0.23.45, application data that a client buffers before the handshake completes is sent to the server even when the server rejects Encrypted Client Hello (ECH).\n\nWhen the server rejects ECH, the client completes the handshake with the outer ClientHello and authenticates the server against the ECH config's `public_name`. At the end of the handshake, `start_traffic()` encrypts and queues any plaintext buffered by `ClientConnection::writer()`. It does this *before* checking for `EchStatus::Rejected` and queueing the `ech_required` alert.\n\nThe application then receives `Error::PeerIncompatible(ServerRejectedEncryptedClientHello)`, as expected. However, the client is still expected to call `write_tls()` to send the fatal alert, and that call also sends the encrypted application data. The server decrypts the data and only then receives the alert.\n\nThe ordering bug is older than 0.23.44. Before 0.23.44, the client checked the server certificate against the inner server name rather than `public_name`, so a correctly configured server failed certificate verification first and no data was sent. 0.23.44 fixed that check, which makes the ordinary rejection path reachable.\n","public_affected_ranges":[">= 0.23.44, < 0.23.46"]},{"certainty":"source_listed","source_ids":["sr-26cf71beee5bbb65749338efe0f52eee"],"technology":"rustls","known_exclusions":[],"conditions_summary":"In rustls 0.23.44 and 0.23.45, application data that a client buffers before the handshake completes is sent to the server even when the server rejects Encrypted Client Hello (ECH).\n\nWhen the server rejects ECH, the client completes the handshake with the outer ClientHello and authenticates the server against the ECH config's `public_name`. At the end of the handshake, `start_traffic()` encrypts and queues any plaintext buffered by `ClientConnection::writer()`. It does this *before* checking for `EchStatus::Rejected` and queueing the `ech_required` alert.\n\nThe application then receives `Error::PeerIncompatible(ServerRejectedEncryptedClientHello)`, as expected. However, the client is still expected to call `write_tls()` to send the fatal alert, and that call also sends the encrypted application data. The server decrypts the data and only then receives the alert.\n\nThe ordering bug is older than 0.23.44. Before 0.23.44, the client checked the server certificate against the inner server name rather than `public_name`, so a correctly configured server failed certificate verification first and no data was sent. 0.23.44 fixed that check, which makes the ordinary rejection path reachable.\n","public_affected_ranges":[">= 0.24.0-dev.1, < 0.24.0-dev.2"]}],"null_published_at":"2026-10-31T22:13:27.121Z","source_updated_at":"2026-10-27T16:09:02.000Z","source_disclosed_at":"2026-10-27T16:08:59.000Z","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":"2026-10-31T21:56:51.534Z"}],"next_cursor":null,"snapshot_revision":"42594"}