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Improper Input ValidationWeakness · CWE-20

CVE-2026-56306

MEDIUM · 6.4 CVSS v3.1 Published 2026-06-22
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

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 weak parsing vulnerability in the x-limited-key-id header that allows attackers to bypass subkey enforcement by submitting malformed values, zero, or duplicate headers that result in NaN or falsy values. Remote attackers can manipulate the x-limited-key-id header to disable limited key scoping and execute requests using the main API key context instead of restricted subkey permissions.

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 · high confidence

Capgo before version 12.128.2 has weak parsing logic for the x-limited-key-id header. Attackers can bypass subkey enforcement by submitting malformed values, zero, or duplicate headers that result in NaN or falsy values, allowing requests to execute with full main API key privileges instead of restricted subkey permissions.

MitigationUpgrade to Capgo 12.128.2 or later which contains proper validation for the x-limited-key-id header to reject malformed, zero, or falsy values.

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
Low
Integrity
Low
Availability
None

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

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. Identify Capgo installation and version
    Locate the Capgo package or service in your environment and retrieve its version number. Check package.json, Docker image tags, or the running service metadata for the installed Capgo version.
    Affected if The installed version is earlier than 12.128.2 (e.g., 12.100.0, 12.127.0, or any version below 12.128.2).
  2. Confirm usage of x-limited-key-id header
    Inspect your API request logs, middleware configuration, or Capgo API client code to determine whether requests are being made with the x-limited-key-id header for subkey enforcement. This header is used to scope API key permissions to limited subkeys.
    Affected if Your application or service makes API calls that include the x-limited-key-id header to enforce subkey restrictions.
  3. Check header validation configuration
    Review Capgo configuration files, environment variables, or API gateway settings related to header validation. Look for any explicit settings that control validation of the x-limited-key-id header value.
    Affected if There is no explicit validation rule configured to reject malformed, zero, duplicate, or falsy values in the x-limited-key-id header, or the validation setting is absent.
  4. Inspect request logs for anomalous header patterns
    Search your API request logs or access logs for requests containing x-limited-key-id headers with values such as: empty strings, null, undefined, 0, NaN, duplicate headers, or non-numeric strings.
    Affected if There are logged requests with x-limited-key-id headers containing malformed, zero, or duplicate values that were processed without rejection.

You are affected if you are running any Capgo version before 12.128.2 AND your system uses the x-limited-key-id header feature to enforce subkey restrictions.

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 contains proper validation for the x-limited-key-id header to reject malformed, zero, or falsy values.

Recommended fix Moderate confidence

12.128.2

  1. 1. Identify the currently installed Capgo version by checking package.json, go.mod, or the running application
  2. 2. If the version is before 12.128.2, upgrade Capgo to version 12.128.2 or later
  3. 3. For npm-based installations: run 'npm update @capgo/capacitor-updater' or 'npm install @capgo/capacitor-updater@latest'
  4. 4. For other package managers, use the appropriate update command (yarn, pnpm)
  5. 5. After upgrading, verify the x-limited-key-id header is now properly validated and rejects malformed values, zero, NaN, or duplicate headers
  6. 6. Test that subkey enforcement cannot be bypassed through manipulation of the x-limited-key-id header
Caveat Review release notes for 12.128.2 to check for any breaking changes in the update

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2026-56306 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

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