What’s Vulnerable › Vulnerabilities
CVE-2026-3416: Predictable Pseudorandom Number Generation via Webhook HMAC Secret Generation in Multiple WSO2 Products Allows Forged Event Payloads
- Severity: high (CVSS 7.5 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.4% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2026-09-03 · updated 2026-09-15
- Weakness: CWE-330
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
- WSO2 Api Control Plane: from 4.5.0 before 4.5.0.53 — fixed in 4.5.0.53
- WSO2 API Manager: from 4.1.0 before 4.1.0.253; from 4.2.0 before 4.2.0.193; from 4.3.0 before 4.3.0.104; from 4.4.0 before 4.4.0.68; from 4.5.0 before 4.5.0.52 — fixed in 4.1.0.253, 4.2.0.193, 4.3.0.104, 4.4.0.68, 4.5.0.52
How to fix
Upgrade to a fixed version: WSO2 Api Control Plane 4.5.0.53; WSO2 API Manager 4.1.0.253, 4.2.0.193, 4.3.0.104, 4.4.0.68. Check the vendor advisory for mitigations.
References
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