CVE-2026-3416: Predictable Pseudorandom Number Generation via Webhook HMAC Secret Generation in Multiple WSO2 Products Allows Forged Event Payloads
The API Publisher component previously used a non-cryptographic pseudorandom number generator (PRNG) to create shared secrets for Webhook HMAC validation. This PRNG lacks sufficient entropy for security-sensitive operations, allowing a sophisticated attacker to predict future secrets. This enables malicious actors to forge event payloads with valid HMAC signatures, bypassing the API Gateway's authenticity verification.
Successful exploitation could allow an attacker to predict shared secrets used for Webhook HMAC validation and forge event payloads with valid signatures. This may enable bypassing API Gateway authenticity checks, leading to unauthorized event injection, data manipulation, or downstream system compromise.
Affected Software
Event History
Frequently Asked Questions
Does an attacker need an account or user interaction to exploit this issue?
No privileges or user interaction are required according to the provided vector. The attacker would need network reachability and sufficient sophistication to predict secrets generated by the affected PRNG.
Which environments are exposed to forged webhook events?
Environments using API Publisher-generated shared secrets for Webhook HMAC validation are exposed if those predictable secrets are in use. A predicted secret can be used to create event payloads with HMAC signatures that pass API Gateway authenticity verification.