# CVE-2026-56233: Capgo path traversal in builder upload proxy

Source: https://junglewise.ai/threats/cve-2026-56233-capgo-path-traversal-in-builder-upload-proxy  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-30. Updated: 2026-07-01  
License: CC BY 4.0 with a link back

CVE-2026-56233 · Severity: high · CVSS 8.3 · Published 2026-06-30

Capgo, a platform for managing mobile app updates, contains a security flaw in its build system. An authorized user could bypass security restrictions to access internal administrative tools by manipulating web addresses. This could allow an attacker to interfere with the app building process, access sensitive internal data, or potentially run unauthorized code within the build environment.

Technologies: [Capgo](https://junglewise.ai/threats/technologies/capgo). Vendors: [Capgo](https://junglewise.ai/threats/vendors/capgo).

## Quick answers

**Is CVE-2026-56233 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-56233 being exploited in the wild.

**How severe is CVE-2026-56233?** High severity, with a CVSS score of 8.3, published 30 June 2026.

**Which products and versions are affected?** Capgo before 12.128.2.

**Is there a fix for CVE-2026-56233?** A patch was published on 2026-06-30: Fix confirmed in version 12.128.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-56233 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-56233?** Check whether you run Capgo at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A path traversal vulnerability exists in the Capgo builder upload proxy (specifically in supabase/functions/_backend/public/build/upload.ts). The application appends user-controlled path segments to the builder upload URL without sanitization. When the request is processed by the WHATWG URL parser in the fetch() API, traversal sequences like '/../' are normalized, allowing an attacker to reach internal administrative endpoints. Because the proxy automatically attaches a privileged BUILDER_API_KEY header to these requests, an authenticated user with build permissions can achieve server-side privilege escalation and SSRF. This allows for the manipulation of build jobs and potential execution of attacker-controlled workloads. The issue is fixed in version 12.128.2.

## Affected products

- Capgo Capgo before 12.128.2

## Timeline

- 2026-03-17: advisory: GitHub Security Advisory published by maintainers
- 2026-06-30: disclosed: NVD and VulnCheck publication date
- 2026-06-30: patched: Fix confirmed in version 12.128.2

## References

- [https://github.com/Cap-go/capgo/security/advisories/GHSA-qprp-873h-mx6f](https://github.com/Cap-go/capgo/security/advisories/GHSA-qprp-873h-mx6f)
- [https://www.vulncheck.com/advisories/capgo-ssrf-and-privilege-escalation-via-path-traversal-in-builder-upload-proxy](https://www.vulncheck.com/advisories/capgo-ssrf-and-privilege-escalation-via-path-traversal-in-builder-upload-proxy)

## Related threats

- [Capgo access control bypass in SSO provider configuration](https://junglewise.ai/threats/cve-2026-100612-capgo-capgo-app-through-version-12-261-0-contains-an-incomplete)
- [Capgo information disclosure in SSO check-domain endpoint](https://junglewise.ai/threats/cve-2026-56336-capgo-information-disclosure-in-sso-check-domain-endpoint)
- [Capgo improper authorization in SSO prelink endpoint](https://junglewise.ai/threats/cve-2026-56313-capgo-improper-authorization-in-sso-prelink-endpoint)
- [Capgo insufficient authentication in email change endpoint](https://junglewise.ai/threats/cve-2026-56308-capgo-insufficient-authentication-in-email-change-endpoint)
- [Capgo SQL injection in admin_stats endpoint](https://junglewise.ai/threats/cve-2026-56281-capgo-sql-injection-in-admin-stats-endpoint)