Vulnerability · Published Sep 3, 2026 · Assigned by WSO2
CVE-2026-3416Predictable Pseudorandom Number Generation via Webhook HMAC Secret Generation in Multiple WSO2 Products Allows Forged Event Payloads
Medium 5.9
In plain English
A medium-severity weak randomness in WSO2 API Control Plane from WSO2. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Official description
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 products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| WSO2 | WSO2 API Manager | 4.1.0 – before 4.1.0.2534.2.0 – before 4.2.0.1934.3.0 – before 4.3.0.1044.4.0 – before 4.4.0.684.5.0 – before 4.5.0.52 |
| WSO2 | WSO2 API Control Plane | 4.5.0 – before 4.5.0.53 |
Weakness: CWE-330 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N