Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck
CVE-2026-79671Ech0 before 4.4.3 SSRF via DNS Resolution Bypass
Medium 5.5
In plain English
A medium-severity server-side request forgery in Ech0 from lin-snow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Ech0 before 4.4.3 contains a server-side request forgery vulnerability in the validateWebhookURL function (webhook_setting_service.go), which only validates literal IP addresses via net.ParseIP() and fails to reject hostnames that DNS-resolve to private or internal IPs (e.g., 169.254.169.254.nip.io). An attacker with admin privileges can create a webhook with such a hostname to bypass validation and cause the server to make requests to internal services, cloud metadata endpoints, and private network resources. The issue is fixed in 4.4.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/lin-snow/ech0 | 4.4.3 | GHSA-r2x7-427f-rq69 |
| Go | github.com/lin-snow/ech0 | no fix listed | GO-2026-5603 |
Affected products (as reported)
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
References
- GitHub Security Advisory (GHSA-r2x7-427f-rq69) vendor-advisory
- VulnCheck Advisory: Ech0 before 4.4.3 SSRF via DNS Resolution Bypass third-party-advisory