CVE-2024-39891
Twilio Authy Information Disclosure Vulnerability
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 status
CISA Known Exploited Vulnerabilities
Listed by CISA on 23 July 2024. US federal agencies were required to remediate it by 13 August 2024.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 1.7%, which is higher than 76.9% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Frequently asked questions
Is CVE-2024-39891 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2024-39891.
What does CVE-2024-39891 affect?
CVE-2024-39891 affects 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.)
How severe is CVE-2024-39891?
CVE-2024-39891 is rated MEDIUM with a CVSS base score of 5.3. EPSS puts the probability of exploitation in the next 30 days at 1.7%, higher than 76.9% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 13 August 2024.
How should organisations respond to CVE-2024-39891?
Apply the vendor patch for Twilio Authy as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.