CVE-2026-56227: Capgo - Server-Side Request Forgery via Webhook URL Validation

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-20 · updated 2026-06-22
Weakness: CWE-918

Description

Capgo before 12.128.2 contains a server-side request forgery vulnerability in webhook URL validation that allows loopback and internal addresses. Organization admins can configure webhooks pointing to localhost or 127.0.0.1, and when triggered, the backend performs outbound requests to these addresses with error responses disclosed to users.

Affected products

Capgo: before 12.128.2 — fixed in 12.128.2

How to fix

Upgrade to a fixed version: Capgo 12.128.2. Check the vendor advisory for mitigations.

References

https://github.com/Cap-go/capgo/security/advisories/GHSA-48hc-53hv-6x3f
https://www.vulncheck.com/advisories/capgo-server-side-request-forgery-via-webhook-url-validation
https://github.com/Cap-go/capgo/security/advisories/GHSA-48hc-53hv-6x3f

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