CVE-2018-5256

CVE-2018-5256 is a high-severity vulnerability in Redhat Tectonic with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Description

CoreOS Tectonic 1.7.x before 1.7.9-tectonic.4 and 1.8.x before 1.8.4-tectonic.3 mounts a direct proxy to the kubernetes cluster at /api/kubernetes/ which is accessible without authentication to Tectonic and allows an attacker to directly connect to the kubernetes API server. Unauthenticated users are able to list all Namespaces through the Console, resulting in an information disclosure. Tectonic's exposure of an unauthenticated API endpoint containing information regarding the internal state of the cluster can provide an attacker with information that may assist in other attacks against the cluster. For example, an attacker may not have the permissions required to list all namespaces in the cluster but can instead leverage this vulnerability to enumerate the namespaces and then begin to check each namespace for weak authorization policies that may allow further escalation of privileges.

Frequently asked questions

What is CVE-2018-5256?
CoreOS Tectonic 1.7.x before 1.7.9-tectonic.4 and 1.8.x before 1.8.4-tectonic.3 mounts a direct proxy to the kubernetes cluster at /api/kubernetes/ which is accessible without authentication to Tectonic and allows an attacker to directly connect to the kubernetes API server. Unauthenticated users are able to list all Namespaces through the Console, resulting in an information disclosure. Tectonic's exposure of an unauthenticated API endpoint containing information regarding the internal state of the cluster can provide an attacker with information that may assist in other attacks against the cluster. For example, an attacker may not have the permissions required to list all namespaces in the cluster but can instead leverage this vulnerability to enumerate the namespaces and then begin to check each namespace for weak authorization policies that may allow further escalation of privileges.
How severe is CVE-2018-5256?
CVE-2018-5256 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2018-5256 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-5256?
CVE-2018-5256 affects Redhat Tectonic. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-5256?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-5256 published?
CVE-2018-5256 was published on 2018-05-18 and last updated on 2026-06-17.

References

Affected products (1)

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