Capgo - Subkey Scope Bypass in middlewareKey via x-limited-key-id Header
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.
- Published
- Jun 24, 2026
- Updated
- Jun 25, 2026
- EPSS
- 0.5% · 39th percentile
- CWE
- CWE-863
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Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.7 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · VulnCheck
- 8.7
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.
Capgo Capgo
- 12.128.2not affected
- before 12.128.2affected · semver
Same product
capgo: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-56237Capgo - Unauthenticated API Key Generation via Client-Side Parameter Manipulation37Monitor
- CVE-2026-56223Capgo - Account Takeover via Cross-Domain SSO Email Assertion in provision-user37Monitor
- CVE-2026-56324Capgo - Rate Limit Bypass via User-Controlled device_id Parameter35Monitor
- CVE-2026-56238Capgo - Unauthenticated Information Disclosure via PostgREST global_stats Endpoint34Monitor
- CVE-2026-56303Capgo - Unauthenticated API Key Metadata Disclosure via SECURITY DEFINER RPC Function34Monitor
- CVE-2026-56305Capgo - Authentication Bypass in Password Change via Missing Current Password Validation34Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Capgo Capgo | 12.128.2 | Vendor (CNA) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Judel777reporter
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-5622014 days apartCapgo - Unauthorized Manifest Insertion via Read-Only Org Member28Monitor
- CVE-2026-5625218 days apartCapgo - Scope Isolation Failure in Webhook Test Endpoint21Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-863 · Incorrect AuthorizationCVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/Cap-go/capgo/security/advisories/GHSA-2h89-vcvx-5pvh
- www.vulncheck.com/advisories/capgo-subkey-scope-bypass-in-middlewarekey-via-x-limited-key-id-header
Vendor advisories and official records. Exploit/PoC links are deliberately left out.