CVE-2024-39891
MediumExploitedPublic exploitIn 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.
Published Jul 2, 2024 · Updated Nov 5, 2025
Key Facts
Patch immediately- CVE-2024-39891 is a medium-severity vulnerability (CVSS 5.3 v3.1) affecting Authy Authenticator (Twilio), Authy (Twilio).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 2, 2024. Public exploit code is available.
- EPSS estimates a 1.7% probability of exploitation in the next 30 days.
- Fixed versions are available, including Authy 26.1.0, Authy Authenticator 25.1.0.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS (30-day exploit likelihood)
1.7%
Higher than 76.4% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2024-39891 brief as a PDF
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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.)
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Jul 23, 2024 | Aug 13, 2024 | Not reported |
| Industry KEV feed | Jul 2, 2024 | Aug 13, 2024 | Not reported |
| CIRCL KEV | Jul 23, 2024 | Aug 13, 2024 | Not reported |
| ENISA EUVD | Jul 23, 2024 | n/a | Not reported |
Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Authy AuthenticatorTwilio | See advisory | 25.1.0 |
| AuthyTwilio | See advisory | 26.1.0 |
Patched Releases
Authy
26.1.0
Authy Authenticator
25.1.0
Timeline
Publicly disclosed
Jul 2, 2024
Added to Industry KEV feed
Jul 2, 2024
Added to CISA KEV
Jul 23, 2024
Added to CIRCL KEV
Jul 23, 2024
Added to ENISA EUVD
Jul 23, 2024
Last updated
Nov 5, 2025
Weakness Type
- CWE-203 Observable Discrepancy
References
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- otherhttps://cwe.mitre.org/data/definitions/203.html
- otherVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Authy Authenticator (Twilio); Authy (Twilio). The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jul 2, 2024.
Yes. It was added on Jul 23, 2024 with a federal remediation due date of Aug 13, 2024.
Public exploit code is available.
Fixed versions are available, including Authy 26.1.0, Authy Authenticator 25.1.0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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