# CVE-2026-3416: WSO2 API Manager weak HMAC secret generation in Webhook

Source: https://junglewise.ai/threats/cve-2026-3416-wso2-api-manager-weak-hmac-secret-generation-in-webhook  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-03. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-3416 · Severity: medium · CVSS 5.9 · Published 2026-09-03

WSO2 API Manager's Webhook feature uses weak random number generation to create HMAC secrets that authenticate event payloads between systems. An attacker with sufficient computational resources could predict these secrets and forge valid webhook messages, allowing unauthorized injection or manipulation of events that downstream systems would trust as legitimate.

Technologies: [Wso2 API Control Plane](https://junglewise.ai/threats/technologies/api-control-plane), [Wso2 API Manager](https://junglewise.ai/threats/technologies/api-manager). Vendors: [Wso2](https://junglewise.ai/threats/vendors/wso2).

## Quick answers

**Is CVE-2026-3416 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-3416 being exploited in the wild.

**How severe is CVE-2026-3416?** Medium severity, with a CVSS score of 5.9, published 3 September 2026.

**Which products and versions are affected?** Wso2 API Control Plane 4.5.0; Wso2 API Manager 4.1.0, 4.2.0, 4.3.0, 4.4.0, 4.5.0.

**Is there a fix for CVE-2026-3416?** A patch was published on 2026-07-04: Updates available for support subscription holders; public fix on GitHub Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-3416 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-3416?** Check whether you run Wso2 API Control Plane or Wso2 API Manager at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The API Publisher component in WSO2 API Manager uses a non-cryptographic pseudorandom number generator (PRNG) to create shared secrets for Webhook HMAC validation, introducing insufficient entropy for security-sensitive operations. The root cause is the use of weak randomness in the secret generation mechanism, making the secrets predictable to a sophisticated attacker with adequate computational resources. Attack vector is network-based and requires no authentication or user interaction; an attacker must perform computational analysis to predict secrets. Successful exploitation enables forging event payloads with valid HMAC signatures, bypassing authenticity checks and potentially leading to unauthorized event injection and downstream system compromise. Patches are available via WSO2 Updates for affected versions (4.1.0 through 4.5.0), with a public GitHub fix at https://github.com/wso2/apim-apps/pull/1279.

## Affected products

- WSO2 API Control Plane 4.5.0
- WSO2 API Manager 4.1.0, 4.2.0, 4.3.0, 4.4.0, 4.5.0

## Timeline

- 2026-07-04: disclosed
- 2026-07-04: patched: Updates available for support subscription holders; public fix on GitHub

## References

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

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