Exploited. On CISA's list since 2024-07-23.
Twilio Authy Information Disclosure Vulnerability
CVE-2024-39891 · Twilio Authy · Published 2024-07-02
How bad would it be?
5.3 out of 10
CVSS rates it medium.
How likely is it to be used?
1.7%
Estimated chance of exploitation in the next 30 days, higher than 76% of all scored flaws (EPSS, 2026-10-29).
Is it already being used?
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 808 days ago (2024-08-13).
What CISA says to do
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Twilio Authy contains an information disclosure vulnerability in its API that allows an unauthenticated endpoint to accept a request containing a phone number and respond with information about whether the phone number was registered with Authy.
What the flaw is
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.)
From the NVD.
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CWE-203 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov. We have not selected a close learning match for this label.
CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.