{"cve":"CVE-2020-24722","nvd":{"published":"2020-10-07T15:15:12.553","modified":"2026-06-17T03:06:02.220","status":"Modified","description":"An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications) protocol through 2020-10-05, as used in COVID-19 applications on Android and iOS. The encrypted metadata block with a TX value lacks a checksum, allowing bitflipping to amplify a contamination attack. This can cause metadata deanonymization and risk-score inflation. NOTE: the vendor's position is \"We do not believe that TX power authentication would be a useful defense against relay attacks.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","score":5.9},"cwes":["CWE-294"],"references":["http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.html","http://seclists.org/fulldisclosure/2020/Oct/12","https://blog.google/inside-google/company-announcements/update-exposure-notifications","https://github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitigations-faq.md#additional-considerations","http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.html"],"products":["exposure_notifications_project:exposure_notifications"],"source":"nvd","synced_at":"2026-10-19T21:09:53.489947993+00:00"},"epss":{"cve":"CVE-2020-24722","score":0.02465,"percentile":0.8448,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}