CVE-2020-24722
** DISPUTED ** An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications)...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
5.9
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.
- Record
CVE-2020-24722- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 2.0
- 2.6 Low
AV:N/AC:H/Au:N/C:N/I:P/A:N - Weakness
- CWE-294
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2020-24722- Updated
- 2026-11-02
EUVDEUVD-2020-17433 No score
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.
- Record
EUVD-2020-17433- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-2gfr-hjcw-mr7q
5.9
** DISPUTED ** An issue was discovered in the GAEN (aka Google/Apple Exposure Notifications)...
** 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."
- Record
GHSA-2gfr-hjcw-mr7q- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-294
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-24722 is a medium vulnerability (CVSS 5.9) in Exposure Notifications Project Notifications, published October 7, 2020. Its validity is disputed. EPSS puts the chance of exploitation in the next 30 days at 2.46%, the 84th percentile.
References
blog.google/inside-google/company-announcements/update-exposure-notifications
seclists.org/fulldisclosure/2020/Oct/12
github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitigations-faq.md
packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.html
nvd.nist.gov/vuln/detail/CVE-2020-24722
github.com/advisories/GHSA-2gfr-hjcw-mr7q