CVE-2020-24722: Exposure Notifications Project Exposure Notifications

Medium severity, CVSS 5.9. EPSS: 2.5% chance of exploitation in the next 30 days.

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.

Affected products

• Exposure Notifications Project Exposure Notifications: up to and including 2020-10-05

Published 2020-10-07. Last modified 2026-06-17.