{"id":"CVE-2020-24722","aliases":["EUVD-2020-17433","GHSA-2gfr-hjcw-mr7q"],"status":"disputed","title":"** DISPUTED ** An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications)...","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.","severity":{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-10","score":0.02465,"percentile":0.84611,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-294"],"published":"2020-10-07T14:07:36Z","modified":"2026-06-17T03:06:02Z","products":[{"vendor":"exposure_notifications_project","product":"exposure_notifications"}],"references":[{"url":"https://blog.google/inside-google/company-announcements/update-exposure-notifications","tags":["x_refsource_MISC","x_transferred","Third Party Advisory"]},{"url":"http://seclists.org/fulldisclosure/2020/Oct/12","tags":["x_refsource_MISC","x_transferred","Exploit","Mailing List","Third Party Advisory"]},{"url":"https://github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitigations-faq.md#additional-considerations","tags":["x_refsource_MISC","x_transferred","Third Party Advisory"]},{"url":"http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.html","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","VDB Entry"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2020-24722"},{"url":"https://github.com/advisories/GHSA-2gfr-hjcw-mr7q"}],"sources":{"cve":[{"id":"CVE-2020-24722","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.","status":"disputed","published":"2020-10-07T14:07:36Z","modified":"2024-08-04T15:19:09.383Z","updated_at":"2026-11-02T14:35:54.468882Z"}],"euvd":[{"id":"EUVD-2020-17433","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.","status":"published","published":"2020-10-07T14:07:36Z","modified":"2024-08-04T15:19:09Z","updated_at":"2026-11-03T03:07:19.210308Z"}],"ghsa":[{"id":"GHSA-2gfr-hjcw-mr7q","title":"** DISPUTED ** An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications)...","description":"** DISPUTED ** 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.\"","status":"published","published":"2022-05-24T17:30:16Z","modified":"2024-03-30T05:01:42Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-294"],"updated_at":"2026-11-02T14:55:44.65747Z"}],"nvd":[{"id":"CVE-2020-24722","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.","status":"disputed","published":"2020-10-07T15:15:12.553Z","modified":"2026-06-17T03:06:02.22Z","cvss":[{"version":"3.1","score":5.9,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"primary"},{"version":"2.0","score":2.6,"vector":"AV:N/AC:H/Au:N/C:N/I:P/A:N","level":"low","assessor":"primary"}],"cwes":["CWE-294"],"updated_at":"2026-11-02T14:06:17.70091Z"}]}}