Phone-number disclosure via unauthenticated account enumeration
Published Jul 2, 2024 · Updated Oct 21, 2025
Information disclosure in Twilio Authy Android before 25.1.0 and Authy iOS before 26.1.0 allows remote attackers to enumerate phone numbers. The unauthenticated API endpoint accepted a stream of supplied phone numbers and returned whether each number was registered with an Authy account. No authentication or user interaction was required; disclosure was limited to associated account data and did not compromise Authy accounts.
Summary
What happened
Information disclosure in Twilio Authy Android before 25.1.0 and Authy iOS before 26.1.0 allows remote attackers to enumerate phone numbers. The unauthenticated API endpoint accepted a stream of supplied phone numbers and returned whether each number was registered with an Authy account. No authentication or user interaction was required; disclosure was limited to associated account data and did not compromise Authy accounts.
The record
- CVE
- CVE-2024-39891
- Published
- Jul 2, 2024
- Updated
- Oct 21, 2025
- Vendor
- Twilio
- Product
- Authy
- Classifications
- CWE-203, T1589
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 1, 2024Exploitation reportedTwilio-reported exploitation
- Jul 2, 2024CVE publishedPublication date reported by the CVE source.
- Jul 23, 2024Exploitation reportedCISA Known Exploited Vulnerabilities listing
- Oct 21, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <25.1.0
- Affected versionversion=0 <26.1.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Reported exploitation
- Twilio-reported exploitationreported exploitation
- CISA Known Exploited Vulnerabilities listingknown exploited catalog
Technologies
Your stack
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Your stack
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