# CVE-2026-56329: Capgo cross-tenant preview namespace collision in hostname parsing

Source: https://junglewise.ai/threats/cve-2026-56329-capgo-cross-tenant-preview-namespace-collision-in-hostname  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-10. Updated: 2026-07-10  
License: CC BY 4.0 with a link back

CVE-2026-56329 · Severity: medium · CVSS 6.4 · Published 2026-07-10

Capgo, a platform for managing app updates and previews, contained a flaw in how it handles application identifiers. An attacker could register a specifically named application that overlaps with another customer's application preview address. This allows the attacker to disrupt the victim's operations by causing their application previews to fail or redirect incorrectly, effectively blocking them from testing or showcasing their work.

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

## Quick answers

**Is CVE-2026-56329 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-56329 being exploited in the wild.

**How severe is CVE-2026-56329?** Medium severity, with a CVSS score of 6.4, published 10 July 2026.

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

**Is there a fix for CVE-2026-56329?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-56329 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-56329?** 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 cross-tenant namespace collision exists in Capgo's preview routing logic due to lossy canonicalization. The preview hostname parser decodes double underscores ('__') into dots ('.') when resolving subdomains, but the application registration logic allows both characters as distinct valid inputs. An attacker with a registered account can create an app ID containing double underscores that resolves to the same preview hostname as a victim's app ID containing dots. This results in an interpretation conflict (CWE-436) where requests for the victim's preview are misrouted to the attacker's application context, leading to a denial of service for the preview functionality. The issue was addressed in version 12.128.2.

## Affected products

- Capgo Capgo < 12.128.2

## Timeline

- 2026-05-07: advisory: GitHub Security Advisory published
- 2026-07-10: disclosed: NVD publication date

## References

- [https://github.com/Cap-go/capgo/security/advisories/GHSA-76qq-gg2p-pwwj](https://github.com/Cap-go/capgo/security/advisories/GHSA-76qq-gg2p-pwwj)
- [https://www.vulncheck.com/advisories/capgo-cross-tenant-preview-namespace-collision-via-non-bijective-underscore-decoding](https://www.vulncheck.com/advisories/capgo-cross-tenant-preview-namespace-collision-via-non-bijective-underscore-decoding)

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