CVE-2024-39891

Name: CVE-2024-39891
Creator: NVD / NIST
Published: 2024-07-02T18:15:03.447+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10Actively ExploitedEPSS 1.48%

Last modified Jun 17, 2026

CVE-2024-39891 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. CISA has confirmed active exploitation in the wild. EPSS estimates a 1.48% chance of exploitation in the next 30 days.

Description

In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before 26.1.0, an unauthenticated endpoint provided access to certain phone-number data, as exploited in the wild in June 2024. Specifically, the endpoint accepted a stream of requests containing phone numbers, and responded with information about whether each phone number was registered with Authy. (Authy accounts were not compromised, however.)

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

1.48%

70.6th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Aug 13, 2024.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Twilio	Authy	< 26.1.0
Twilio	Authy Authenticator	< 25.1.0

References

https://cwe.mitre.org/data/definitions/203.htmlTechnical Description
https://www.bleepingcomputer.com/news/security/hackers-abused-api-to-verify-millions-of-authy-mfa-phone-numbers/Press/Media Coverage
https://www.twilio.com/docs/usage/security/reporting-vulnerabilitiesProduct
https://www.twilio.com/en-us/changelogRelease Notes
https://cwe.mitre.org/data/definitions/203.htmlTechnical Description
https://www.bleepingcomputer.com/news/security/hackers-abused-api-to-verify-millions-of-authy-mfa-phone-numbers/Press/Media Coverage
https://www.twilio.com/docs/usage/security/reporting-vulnerabilitiesProduct
https://www.twilio.com/en-us/changelogRelease Notes
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-39891US Government Resource

Timeline

Published: Jul 2, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2024-39891?

How severe is CVE-2024-39891?

CVE-2024-39891 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 1.48% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2024-39891?

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-2024-39891?

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

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Source: NVD / NIST