---
title: "CVE-2024-39891: Twilio Authy Information Disclosure Vulnerability"
url: https://erroneo.us/security/cve/CVE-2024-39891/
description: "CVE-2024-39891 (Twilio Authy): Exploited in the wild (CISA KEV). In the Twilio Authy API, accessed by Authy Android before 25.1.0 and Authy iOS before…"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-07-02
date_modified: 2025-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2024-39891"
kev: true
cvss: 5.3
epss: 0.01669
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2024-39891: Twilio Authy Information Disclosure Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Twilio Authy. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2024-07-23, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2024-08-13 ; treat that as the outer limit, not the target.
- EPSS 1.7% , percentile 77: FIRST’s model estimates a 1.7% chance of exploitation activity in the next 30 days, higher than 77% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it 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.)

## Affected products (CVE record)

- n/a n/a: see advisory

## Severity

- mitre CVSS 3.1: 5.3 `CVSS:3.1/AC:L/AV:N/A:N/C:L/I:N/PR:N/S:U/UI:N`

## Exploitation

- CISA KEV: added 2024-07-23; federal due date 2024-08-13. Known ransomware use: Unknown.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 1.67% probability of exploitation activity in the next 30 days; percentile 77.

## Sources

- [Listed in CISA KEV notes (twilio.com)](https://www.twilio.com/en-us/changelog/Security_Alert_Authy_App_Android_iOS)
- [CVE.org record CVE-2024-39891](https://www.cve.org/CVERecord?id=CVE-2024-39891)
- [NVD entry CVE-2024-39891](https://nvd.nist.gov/vuln/detail/CVE-2024-39891)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-39891)
- [cwe.mitre.org](https://cwe.mitre.org/data/definitions/203.html)
- [twilio.com](https://www.twilio.com/docs/usage/security/reporting-vulnerabilities)
- [twilio.com](https://www.twilio.com/en-us/changelog)
- [bleepingcomputer.com](https://www.bleepingcomputer.com/news/security/hackers-abused-api-to-verify-millions-of-authy-mfa-phone-numbers/)

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Source page: https://erroneo.us/security/cve/CVE-2024-39891/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt