CVE-2020-24722

Name: CVE-2020-24722
Creator: NVD / NIST
Published: 2020-10-07T15:15:12.553+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 2.44%

Last modified Jun 17, 2026

CVE-2020-24722 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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. EPSS estimates a 2.44% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

2.44%

82.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-294

Affected Software

Vendor	Product	Versions
Exposure Notifications Project	Exposure Notifications	<= 2020-10-05

References

http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2020/Oct/12Exploit, Mailing List, Third Party Advisory
https://blog.google/inside-google/company-announcements/update-exposure-notificationsThird Party Advisory
https://github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitigations-faq.md#additional-considerationsThird Party Advisory
http://packetstormsecurity.com/files/159496/GAEN-Protocol-Metadata-Deanonymization-Risk-Score-Inflation.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2020/Oct/12Exploit, Mailing List, Third Party Advisory
https://blog.google/inside-google/company-announcements/update-exposure-notificationsThird Party Advisory
https://github.com/google/exposure-notifications-internals/blob/main/en-risks-and-mitigations-faq.md#additional-considerationsThird Party Advisory

Timeline

Published: Oct 7, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-24722?

How severe is CVE-2020-24722?

CVE-2020-24722 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 2.44% probability of exploitation in the next 30 days.

How do I fix CVE-2020-24722?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-24722?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST