# CVE-2026-56306: Capgo - Subkey Enforcement Bypass via x-limited-key-id Header Parsing

> Attackers can bypass subkey restrictions by manipulating the x-limited-key-id header, allowing execution of requests with main API key privileges.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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:** 22 Jun 2026
- **Updated:** 23 Jun 2026
- **Also known as:** GHSA-42vv-8j94-24wj

## What is CVE-2026-56306?

CVE-2026-56306 is a medium-severity authentication bypass vulnerability in Capgo, published on 22 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-56306?


## How do I fix CVE-2026-56306?

No fix has been published for CVE-2026-56306 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56306 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56306 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56306 and fix it if it is affected.

What it is: CVE-2026-56306 is a medium-severity authentication bypass vulnerability in Capgo, published on 22 Jun 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-2026-56306 exists.

Affected product: Capgo. 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-2026-56306/ (Markdown: https://insights.sbomify.com/CVE-2026-56306/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56306
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56306
- OSV: https://osv.dev/vulnerability/CVE-2026-56306

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56306/
Summaries are generated and may contain mistakes; the official description above is the record.