CVE-2026-56232: Capgo - Subkey Scope Bypass in middlewareKey via x-limited-key-id Header

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-24 · updated 2026-10-25
Weakness: CWE-863

Description

Capgo before 12.128.2 fails to enforce limited_to_orgs and limited_to_apps constraints on subkeys provided via x-limited-key-id header in middlewareKey function. Attackers can bypass subkey scope restrictions by referencing their own subkeys, causing all downstream route handlers to use the unrestricted parent key instead of the scoped subkey.

Affected products

Capgo: before 12.128.2 — fixed in 12.128.2

How to fix

Upgrade to a fixed version: Capgo 12.128.2. Check the vendor advisory for mitigations.

References

https://github.com/Cap-go/capgo/security/advisories/GHSA-2h89-vcvx-5pvh
https://www.vulncheck.com/advisories/capgo-subkey-scope-bypass-in-middlewarekey-via-x-limited-key-id-header
https://github.com/Cap-go/capgo/security/advisories/GHSA-2h89-vcvx-5pvh

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