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CWE-436Weakness · CWE-436

CVE-2026-56329

MEDIUM · 6.4 CVSS v3.1 Published 2026-07-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
Remotely reachable Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Capgo before 12.128.2 contains a cross-tenant preview namespace collision vulnerability caused by non-bijective decoding of double underscores to dots in preview hostname parsing. Attackers can register app IDs with underscores that collide with other tenants' dotted app IDs, causing preview misrouting and denial of preview access for victim applications.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Capgo before 12.128.2 has a cross-tenant namespace collision where the preview hostname parser non-bijectively decodes double underscores (__) to dots (.), causing collisions between app IDs containing underscores and legitimate dotted app IDs from other tenants. Attackers can register app IDs with underscores that map to existing dotted app IDs, causing preview traffic to be misrouted and denying legitimate users access to their previews.

MitigationUpgrade to Capgo 12.128.2 or later, which fixes the non-bijective decoding logic in preview hostname parsing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Capgo version
    Run the Capgo CLI command to get the installed version, such as `capgo --version` or check the package.json if self-hosting, then compare it to 12.128.2
    Affected if Version is below 12.128.2
  2. Identify app IDs with underscores
    Query your Capgo application database or use the Capgo API to list all registered app IDs and filter for those containing double underscores (__)
    Affected if Any app IDs containing double underscores (__) exist in your tenant
  3. Check for collision risk with dotted app IDs
    For each app ID containing underscores, replace each double underscore (__) with a single dot (.) and query whether a different tenant owns an app ID matching that dotted version
    Affected if A dotted version of an underscore-containing app ID exists in a different tenant, indicating a possible collision
  4. Verify preview hostnames are in use
    Review Capgo logs or configuration to confirm that preview hostname routing is active; check for requests to preview.* hostnames
    Affected if Preview functionality is enabled and in use, which is required for the misrouting to occur

A user is affected if they run Capgo below version 12.128.2 AND have underscore-containing app IDs that could collide with dotted app IDs from other tenants while using preview hostnames.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Capgo 12.128.2 or later, which fixes the non-bijective decoding logic in preview hostname parsing.

Recommended fix Moderate confidence

12.128.2 or later

  1. Identify the current installed version of Capgo in your environment
  2. Consult Capgo's official release notes or GitHub repository for version 12.128.2 to confirm the fix includes the cross-tenant preview namespace collision remediation
  3. Plan the upgrade considering your deployment method (npm, yarn, or other package manager)
  4. Execute the upgrade command appropriate to your package manager (e.g., npm update @capgo/cli or equivalent)
  5. After upgrading, verify the application ID naming conventions in your tenant to ensure no unintended collisions occur
  6. Test preview functionality to confirm the vulnerability is remediated

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-56329 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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