Security Digest · Vulnerability record · Known exploited
CVE-2024-39891: Twilio Authy Information Disclosure Vulnerability
Exploited in the wild (CISA KEV). 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.
CISA KEV · added 2024-07-23 CVSS 5.3 Medium EPSS 1.7% · p77
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- 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.)
CISA’s summary
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.
Weakness type: CWE-203.
Product: Twilio Authy · Assigned by: mitre · Published: 2024-07-02
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| n/a | n/a | see vendor advisory |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| mitre | 3.1 | 5.3 Medium | CVSS:3.1/AC:L/AV:N/A:N/C:L/I:N/PR:N/S:U/UI:N |
- Attack complexity: low
- Attack vector: network (remotely reachable)
- Privileges required: none (no login)
- Scope: unchanged
- User interaction: none
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- 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.
Timeline
- — CVE record published by mitre
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- Listed in CISA KEV notes (twilio.com) twilio.com
Vulnerability records
- CVE.org record CVE-2024-39891 cve.org
- NVD entry CVE-2024-39891 nvd.nist.gov
Government
Other references from the CVE record and advisory
- cwe.mitre.org cwe.mitre.org
- twilio.com twilio.com
- twilio.com twilio.com
- bleepingcomputer.com bleepingcomputer.com
All exploited Twilio vulnerabilities · Today’s Security Digest