CVE-2022-31055: Improper Access Control in kctf

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-06-13 · updated 2026-06-17
Weakness: CWE-284

Description

kCTF is a Kubernetes-based infrastructure for capture the flag (CTF) competitions. Prior to version 1.6.0, the kctf cluster set-src-ip-ranges was broken and allowed traffic from any IP. The problem has been patched in v1.6.0. As a workaround, those who want to test challenges privately can mark them as `public: false` and use `kctf chal debug port-forward` to connect.

Affected products

google kctf: before 1.6.0 — fixed in 1.6.0

How to fix

Upgrade to a fixed version: google kctf 1.6.0. Check the vendor advisory for mitigations.

References

https://github.com/google/kctf/commit/8cf050be974fcc2fd8aa136701f9a66f2b2a5202
https://github.com/google/kctf/pull/371
https://github.com/google/kctf/security/advisories/GHSA-4g2v-6qc6-6jv5
https://github.com/google/kctf/commit/8cf050be974fcc2fd8aa136701f9a66f2b2a5202
https://github.com/google/kctf/pull/371
https://github.com/google/kctf/security/advisories/GHSA-4g2v-6qc6-6jv5

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