# CVE-2026-61682: kcp front-proxy header injection and privilege escalation

Source: https://junglewise.ai/threats/cve-2026-61682-kcp-front-proxy-header-injection-and-privilege-escalation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-18. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-61682 · Severity: critical · CVSS 9.9 · Published 2026-09-18

kcp front-proxy is a Kubernetes proxy used in multi-tenant deployments to route and authenticate requests between clients and cluster shards. An authenticated user can inject forged identity headers to falsely claim system administrator privileges and access any tenant's data across the cluster, breaking the core isolation that protects each customer's workloads and resources.

Technologies: [github.com/kcp-dev/kcp (Go)](https://junglewise.ai/threats/technologies/github-com-kcp-dev-kcp). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-61682 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-61682 being exploited in the wild.

**How severe is CVE-2026-61682?** Critical severity, with a CVSS score of 9.9, published 18 September 2026.

**Which products and versions are affected?** github.com/kcp-dev/kcp (Go) SEMVER:introduced=0,fixed=0.31.4, SEMVER:introduced=0,fixed=0.31.4,introduced=0.32.0,fixed=0.32.2; Kcp before 0.31.4, before 0.32.2.

**Is there a fix for CVE-2026-61682?** Yes. github.com/kcp-dev/kcp (Go): upgrade to 0.31.4, 0.32.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-61682 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-61682?** Check whether you run github.com/kcp-dev/kcp (Go) or Kcp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/kcp-dev/kcp (Go): upgrade to 0.31.4, 0.32.2 or later

  ```sh
  go get github.com/kcp-dev/kcp@v0.32.2
  ```


## Technical details

The vulnerability is a request-header spoofing and privilege escalation flaw in kcp's front-proxy authentication chain. The front-proxy authenticates clients and forwards their identity to downstream shards via Kubernetes request-header authentication headers (X-Remote-User, X-Remote-Group, X-Remote-Extra-*). The root cause is that the proxy appends its verified identity headers instead of replacing any client-supplied copies, allowing an authenticated attacker to inject forged headers (e.g., X-Remote-Group: system:masters) that the shard trusts as verified identity assertions. An attacker with any valid credential (certificate, OIDC token, or service account) can assert cluster administrator privileges, bypass authorization policies, forge delegated-identity warrants, and access any workspace's secrets and RBAC configuration. The fix (v0.31.4, v0.32.2) unconditionally strips all inbound X-Remote-* headers before authentication to prevent client-supplied values from reaching the shard.

## Affected products

- kcp kcp before 0.31.4, before 0.32.2

## Identifiers

- CVE-2026-61682
- GHSA-c8w2-fgvx-vhv4
- GO-2026-6517

## Timeline

- 2026-09-18: disclosed
- 2026-09-18: patched: v0.31.4 and v0.32.2 released

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