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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 th...

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw exposed Kubernetes namespace information through a Tectonic Console proxy path without requiring Tectonic authentication. It is primarily an information disclosure issue, but namespace enumeration can help attackers plan follow-on attacks against weak cluster authorization boundaries.

Executive priority

Prioritize if legacy Tectonic clusters remain in use. The direct business risk is information disclosure, but exposed cluster structure can reduce attacker effort during broader Kubernetes compromise attempts.

Technical view

CoreOS Tectonic 1.7.x before 1.7.9-tectonic.4 and 1.8.x before 1.8.4-tectonic.3 mounted an unauthenticated proxy at /api/kubernetes/. That proxy allowed unauthenticated access to list all Kubernetes namespaces through the Console, revealing internal cluster state.

Likely exposure

Exposure is limited to organizations that still run the affected CoreOS Tectonic versions and have the vulnerable Console/API proxy reachable by unauthenticated users.

Exploitation context

The provided sources do not state active exploitation, and this CVE is not marked as CISA KEV. The disclosed impact is namespace enumeration, which may support later authorization probing or privilege escalation attempts.

Researcher notes

Evidence is confined to the CVE description and CoreOS references. No CVSS, CWE, exploit confirmation, or detailed vendor workaround is present in the supplied bundle.

Mitigation direction

  • Upgrade Tectonic 1.7.x to 1.7.9-tectonic.4 or later.
  • Upgrade Tectonic 1.8.x to 1.8.4-tectonic.3 or later.
  • Review the CoreOS advisory and release notes for upgrade guidance.
  • Treat exposed Tectonic Console access as sensitive until fixed.

Validation and detection

  • Inventory any remaining CoreOS Tectonic clusters.
  • Check exact Tectonic versions against the fixed releases.
  • Confirm whether /api/kubernetes/ is reachable without authentication.
  • Review logs for unauthenticated Console access patterns.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2018-5256 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.