# CVE-2026-61682: kcp front-proxy does not strip inbound X-Remote-* identity headers, allowing any authenticated client to inject groups/warrants and impersonate system:masters in any workspace

> Authenticated clients can inject identity headers to impersonate system:masters, bypassing authorization to read, write, or delete resources across workspaces.

- **Severity:** Critical 9.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 21 Sep 2026
- **Also known as:** GHSA-c8w2-fgvx-vhv4, GO-2026-6517

## What is CVE-2026-61682?

CVE-2026-61682 is a critical authentication bypass vulnerability in kcp-dev kcp, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

kcp is a Kubernetes-like control plane for form-factors and use-cases beyond Kubernetes and container workloads. Prior to 0.31.4 and 0.32.2, the kcp front-proxy does not remove inbound X-Remote-User, X-Remote-Group, or X-Remote-Extra-* identity headers before forwarding requests to shards. Any authenticated tenant can inject X-Remote-Group: system:masters, authorization.kcp.io/warrant, authentication.kcp.io/scopes, or a group used for per-workspace required-group gating, and the shard trusts these values as authenticated identity assertions. This allows cross-workspace impersonation, authorization bypass, and arbitrary reading, writing, or deletion of resources, secrets, RBAC data, APIExports, APIBindings, and LogicalClusters. This issue is fixed in versions 0.31.4 and 0.32.2.

Weakness: CWE-348 (Use of Less Trusted Source), CWE-302 (Authentication Bypass by Assumed-Immutable Data), CWE-290 (Authentication Bypass by Spoofing)

## Which versions are affected by CVE-2026-61682?

5 open source packages ship an affected version, including github.com/kcp-dev/kcp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/kcp-dev/kcp` | Go | All versions | 0.31.4, 0.32.2 |
| `github.com/kcp-dev/kcp` | Go | All versions | 0.31.4 |
| `github.com/kcp-dev/kcp` | Go | All versions | 0.31.4 |
| `github.com/kcp-dev/kcp` | Go | From 0.32.0 | 0.32.2 |
| `github.com/kcp-dev/kcp` | Go | From 0.32.0 | 0.32.2 |

## How do I fix CVE-2026-61682?

Upgrade github.com/kcp-dev/kcp to a fixed version for your release line: 0.31.4 or 0.32.2.

## Is CVE-2026-61682 being exploited?

There is no known exploitation of CVE-2026-61682 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61682 and fix it if it is affected.

What it is: CVE-2026-61682 is a critical authentication bypass vulnerability in kcp-dev kcp, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-61682 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/kcp-dev/kcp (Go): affected all versions; fixed in 0.31.4, 0.32.2
- github.com/kcp-dev/kcp (Go): affected all versions; fixed in 0.31.4
- github.com/kcp-dev/kcp (Go): affected all versions; fixed in 0.31.4
- github.com/kcp-dev/kcp (Go): affected from 0.32.0; fixed in 0.32.2
- github.com/kcp-dev/kcp (Go): affected from 0.32.0; fixed in 0.32.2

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-2026-61682/ (Markdown: https://insights.sbomify.com/CVE-2026-61682/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61682
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61682
- OSV: https://osv.dev/vulnerability/CVE-2026-61682

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61682/
Summaries are generated and may contain mistakes; the official description above is the record.