CVE intelligence and bounded remediation

CVE-2020-24655 — Twilio Authy 2-Factor Authentication security vulnerability

Medium CVSS 5.1

A race condition in the Twilio Authy 2-Factor Authentication application before 24.3.7 for Android allows a user to potentially approve/deny an access request prior to unlocking the application with a PIN on older Android devices (effectively bypassing the PIN requirement).

Severity
Medium
CVSS
5.1 (3.1)
Published
2020-09-10
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-362

Affected products

  • twilio / authy_2-factor_authentication / 24.3.7

Matched remediation archetype

Race condition, TOCTOU, and lifecycle synchronization

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Check exposure

  • Map concurrent actors, shared state, lock boundaries, signals, callbacks, retries, and check-then-use sequences in the affected path.
  • Determine whether untrusted users can influence timing, object names, filesystem state, or repeated state transitions.
  • Identify clustered and multi-process behavior that repository-local tests may not represent.

Remediate safely

  • Make the sensitive state transition atomic or protect it with a consistently ordered synchronization primitive.
  • Perform authorization and invariant checks on the same authoritative object and transaction used for the operation.
  • Use unique private resources, safe ownership transfer, and idempotent operations; add deterministic concurrency regression tests.

Authoritative sources

Complete CVE record and remediation plan

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