IRONSMITHINTEL
MEDIUMCVSS5.3
|
Actively Exploited
|CISA KEV|CVE-2024-39891|Auth: none — unauthenticated|Reboot: required|Manual only

Twilio Authy Information Disclosure Vulnerability

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.

Published Jul 2, 2024 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure. Federal agencies are required to remediate by 2024-08-13 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-203) (CWE-203) vulnerability in Twilio Authy. 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.) Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

📧

Phishing link

🖼

Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running authy: v < 26.1.0; authy authenticator: v < 25.1.0
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://cwe.mitre.org/data/definitions/203.html

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

References

    1
    Vendor advisory: https://www.twilio.com/en-us/changelog/Security_Alert_Authy_App_Android_iOS
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2024-39891
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-39891
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