Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The Go package github.com/lin-snow/ech0 is vulnerable in versions before 4.4.3. Its webhook URL validation checks only literal IP addresses, so a hostname that resolves to a private or internal address is accepted. An authenticated admin can create a webhook that makes the server send requests to internal services, including cloud metadata endpoints. Upgrade to version 4.4.3 or later, which is the listed fix.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.1 | Medium | 4.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N | CNA (VulnCheck) |
- CISA KEV Not listed.
- EPSS 0.0031, the 24th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:48 UTC First seen by agentprime
- 31 Oct 2026, 14:48 UTC Confirmed by OSV