# CVE-2026-88862: Capgo API Key Manager Authentication Bypass via x-limited-key-id

> Authenticated attackers can bypass API key restrictions by supplying a privileged key ID in headers, gaining unauthorized application admin permissions.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** GHSA-5hjr-xhx8-x5j7, GHSA-92q7-3qv3-754g

## What is CVE-2026-88862?

CVE-2026-88862 is a high-severity authentication bypass vulnerability in Cap-go capgo.app, published on 10 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Capgo (capgo.app) backend through 12.242.4 does not validate parent-child delegation when processing the x-limited-key-id header. checkKeyByIdPg() in supabase/functions/_backend/utils/hono_middleware.ts resolves the attacker-supplied numeric API key ID using only the key ID, its expiration state, and the authenticating key's user_id, while hasLimitedRbacSubkeyScope() accepts any key with a non-organization (e.g., app-scoped) RBAC binding and validateSubkeyUser() only compares owning user IDs. Because Capgo treats API keys as independent RBAC principals with separate role bindings, an authenticated apikey_manager API key with no application access can supply the numeric ID of a more privileged same-owner key and have the middleware replace the authenticated principal and effective API-key secret with that key (setSubkeyAuthContext), exercising an app_admin sibling's permissions without knowing or submitting its secret. The issue was reproduced on release 12.242.4 (commit b3d02cdbc23ac59990785acacd1f113c07458568) after the fix for GHSA-8h52-44r7-w343; at the time of the advisory no patched version was available.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-88862?


## How do I fix CVE-2026-88862?

No fix has been published for CVE-2026-88862 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-88862 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88862 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88862 and fix it if it is affected.

What it is: CVE-2026-88862 is a high-severity authentication bypass vulnerability in Cap-go capgo.app, published on 10 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88862 exists.

Affected product: Cap-go capgo.app. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-88862/ (Markdown: https://insights.sbomify.com/CVE-2026-88862/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88862
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88862
- OSV: https://osv.dev/vulnerability/CVE-2026-88862

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-88862/
Summaries are generated and may contain mistakes; the official description above is the record.