Active Incident
Confirmed: historical blocking: CN 2021-12-22
China · December 22, 2021 · 1 day
Backfilled from OONI historical archive. 1 anomalous day(s), 2 measurements, 100% anomaly rate. Signal types: block, interference. Signal levels: critical.
Evidence
100%
Anomaly Rate
2
Measurements
98%
Confidence
What This Means
100% of 2 network tests from China failed to reach these services. Global baseline failure rate is typically 1-3%. This 97+ percentage point difference strongly indicates intentional blocking.
How We Detected This
Data Sourceooni-historical-backfill
ML ModelGradientBoosting v3.3 (LOCO median F1 0.87, honest across 127 countries)
Confidence Score98% certainty of censorship
Detection TimeDecember 22, 2021
What we cannot say
- Who caused it — measurement data alone does not attribute this to any government, ISP, or other actor.
- Intent — anomalous or unreachable measurements indicate interference, not a stated motive or a deliberate-vs-incidental determination.
- Which networks — no specific ASN/ISP is identified for this incident.
- The mechanism — we cannot state whether this was DNS tampering, TLS/SNI reset, an HTTP blockpage, throttling, or an infrastructure outage.
- Sub-national scope — measurement is aggregated at the country level; we cannot localize to a province, city, or network segment.
- Independent corroboration — this rests on a single source; treat it as a single-source signal, not a multi-source confirmation.
Cite This Incident
Voidly Research. (2021). Confirmed: historical blocking: CN 2021-12-22 [CN-2021-0007]. Voidly Global Censorship Index. https://voidly.ai/incident/CN-2021-0007