CVE-2026-56336: Capgo - Information Disclosure via Unauthenticated SSO check-domain Endpoint

Severity: medium (CVSS 5.3 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: 2026-07-12 · updated 2026-09-17
Weakness: CWE-200

Description

Capgo before 12.128.2 contains an information disclosure vulnerability in the unauthenticated /private/sso/check-domain endpoint that returns internal org_id and provider_id values. Attackers can enumerate email domains to build mappings of domains to organization UUIDs and SSO provider identifiers, enabling reconnaissance against Capgo tenants.

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-c5jf-5wxg-mgrq
https://www.vulncheck.com/advisories/capgo-information-disclosure-via-unauthenticated-sso-check-domain-endpoint
https://github.com/Cap-go/capgo/security/advisories/GHSA-c5jf-5wxg-mgrq

Get alerted when CVE-2026-56336 or the next vulnerability affects your stack