# CVE-2026-79671: Ech0 server-side request forgery in webhook URL validation

Source: https://junglewise.ai/threats/cve-2026-79671-ech0-server-side-request-forgery-in-webhook-url-validation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-25. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-79671 · Severity: medium · CVSS 5.5 · Published 2026-08-25

Ech0 is a monitoring and alerting system that processes webhooks to notify administrators of application events. The webhook URL validation function fails to properly check hostnames that resolve to internal or cloud metadata IP addresses, allowing authenticated admins to create webhooks targeting internal services and steal sensitive data like cloud credentials. This undermines the application's intended security boundary and enables reconnaissance of internal network infrastructure.

Technologies: [github.com/lin-snow/ech0 (Go)](https://junglewise.ai/threats/technologies/github-com-lin-snow-ech0). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-79671 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-79671 being exploited in the wild.

**How severe is CVE-2026-79671?** Medium severity, with a CVSS score of 5.5, published 25 August 2026.

**Which products and versions are affected?** github.com/lin-snow/ech0 (Go) SEMVER:introduced=0, SEMVER:introduced=0,fixed=4.4.3.

**Is there a fix for CVE-2026-79671?** Yes. github.com/lin-snow/ech0 (Go): upgrade to 4.4.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-79671 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-79671?** Check whether you run github.com/lin-snow/ech0 (Go) 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.

## How to fix

- github.com/lin-snow/ech0 (Go): upgrade to 4.4.3 or later

  ```sh
  go get github.com/lin-snow/ech0@v4.4.3
  ```


## Technical details

The vulnerability is a server-side request forgery (SSRF) in the validateWebhookURL function (webhook_setting_service.go:180-199) caused by incomplete IP address validation. The function uses net.ParseIP() to detect private IPs, but this only matches literal IP strings and returns nil for hostnames. Attackers with admin privileges can craft URLs like "http://169.254.169.254.nip.io/latest/meta-data/" that pass validation yet resolve to private addresses. Once stored, active webhooks automatically fire on every application event via Dispatcher.HandleObservation without re-validation, enabling persistent outbound requests to internal services, cloud metadata endpoints (AWS, GCP, Azure), and internal network resources. The fix requires implementing a custom DNS-resolving dialer that validates resolved IPs before connection. Patched in version 4.4.3.

## Affected products

- Ech0 Ech0 before 4.4.3

## Identifiers

- CVE-2026-79671
- GHSA-r2x7-427f-rq69
- GO-2026-5603

## Timeline

- 2026-04-09: disclosed: GitHub security advisory published
- 2026-08-25: advisory: NVD and public vulnerability disclosure
- 2026-04-09: patched: Fix available in version 4.4.3

## References

- [https://github.com/lin-snow/Ech0/security/advisories/GHSA-r2x7-427f-rq69](https://github.com/lin-snow/Ech0/security/advisories/GHSA-r2x7-427f-rq69)
- [https://www.vulncheck.com/advisories/ech0-before-ssrf-via-dns-resolution-bypass](https://www.vulncheck.com/advisories/ech0-before-ssrf-via-dns-resolution-bypass)

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