What’s Vulnerable › Vulnerabilities

CVE-2020-24722

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-10-07 · updated 2026-06-17
• Weakness: CWE-294

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.

Affected products

• Exposure Notifications Project Exposure Notifications: through 2020-10-05

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
• 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

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