Auth bypass in Kcp
CVE-2026-39429
kcp is a Kubernetes-like control plane for form-factors and use-cases beyond Kubernetes and container workloads. Prior to 0.30.3 and 0.29.3, the cache server is directly exposed by the root shard and has no authentication or authorization in place. This allows anyone who can access the root shard to read and write to the cache server. This vulnerability is fixed in 0.30.3 and 0.29.3.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (37.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.004 · change: -0.001
Affected products
- Kcp
- Kcp-Dev Kcp — versions >= 0.30.0, < 0.30.3, < 0.29.3
Weakness classification (CWE)
References
- github.com/kcp-dev/kcp/security/advisories/GHSA-3j3q-wp9x-585p (Exploit, Mitigation, Vendor Advisory)
- github.com/kcp-dev/kcp/releases/tag/v0.29.3 (Release Notes)
- github.com/kcp-dev/kcp/releases/tag/v0.30.3 (Release Notes)
Frequently asked questions
- What is CVE-2026-39429?
- CVE-2026-39429 is a high-severity vulnerability in Kcp, classified under Authentication Bypass by Assumed-Immutable Data. CVSS score: 8.2/10. Published 2026-04-08.
- How severe is CVE-2026-39429?
- High severity. CVSS v3 base score is 8.2 out of 10.