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Fencer Vulns
high 8.2

CVE-2026-39429 json

kcp's cache server is accessible without authentication or authorization checks

published 2026-04-08 7 mo ago modified 2026-09-10 1 mo ago also GHSA-3j3q-wp9x-585p , GO-2026-5088 , EUVD-2026-20607

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/kcp-dev/kcp 0.29.3, 0.30.3
  • kcp kcp 0.29.3, 0.30.3
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/kcp-dev/kcp/security/advisories/GHSA-3j3q-wp9x-585p referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
GitHub 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/kcp-dev/kcp
>=0.30.0, <0.30.3
<0.29.3
0.30.3
0.29.3

Affected products

  • kcp-dev kcp

Classification

Weakness
  • CWE-862 Missing Authorization
  • CWE-302 Authentication Bypass by Assumed-Immutable Data
  • CWE-306 Missing Authentication for Critical Functionality

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.