# CVE-2024-39891: Twilio Authy Information Disclosure

> An unauthenticated API endpoint in Twilio Authy mobile apps leaked registration status for phone numbers, allowing attackers to identify registered users.

- **Severity:** Medium 5.3 (`CVSS:3.1/AC:L/AV:N/A:N/C:L/I:N/PR:N/S:U/UI:N`)
- **Exploited in the wild:** Yes, since 23 Jul 2024 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Jul 2024
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-vg5j-h7r8-88x8

## What is CVE-2024-39891?

CVE-2024-39891 is a medium-severity vulnerability in n/a, published on 2 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.)

Weakness: CWE-203 (Observable Discrepancy)

## Which versions are affected by CVE-2024-39891?

It affects 2 products.


Products: Twilio Authy, Twilio Authy Authenticator.

## How do I fix CVE-2024-39891?

No fix has been published for CVE-2024-39891 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 13 Aug 2024.

## Is CVE-2024-39891 being exploited?

Yes. Attackers have exploited CVE-2024-39891 in the wild since at least 23 Jul 2024.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-39891 and fix it if it is affected.

What it is: CVE-2024-39891 is a medium-severity vulnerability in n/a, published on 2 Jul 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2024-39891 in the wild since at least 23 Jul 2024.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-39891/ (Markdown: https://insights.sbomify.com/CVE-2024-39891/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-39891
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-39891
- OSV: https://osv.dev/vulnerability/CVE-2024-39891

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-39891/
Summaries are generated and may contain mistakes; the official description above is the record.