CVE-2026-22872: capsule Input Validation Flaw — Exploit

Description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. The Capsule Controller runs with cluster-admin privileges. Although the TenantResource RawItems processing logic forcibly sets the namespace, this is ineffective for cluster-scoped resources. Prior to version 0.13.0, tenant administrators can leverage the Controller's elevated privileges to create cluster-scoped resources (such as ClusterRole and ValidatingWebhookConfiguration) that they cannot create directly, achieving cross-tenant privilege escalation and cluster-level attacks. The attack vector has a few limiting factors. This attack requires Tenant Owner privileges and requires Capsule Controller running with cluster-admin privileges (default configuration). Additionally, some clusters may have additional admission controllers blocking malicious resources. Version 0.13.0 patches this issue.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0043

Probability of exploitation

0.34%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-863 Incorrect Authorization

Affected Products

Vendor	Product	Versions
projectcapsule	capsule	< 0.13.0

References

Advisories & Patches

https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72 https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72

Exploits

https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72 https://github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm-7j9w-pw72

Other References

https://github.com/projectcapsule/capsule/releases/tag/v0.13.0

Frequently Asked Questions

What is CVE-2026-22872? +

Capsule is a multi-tenancy and policy-based framework for Kubernetes. The Capsule Controller runs with cluster-admin privileges. Although the TenantResource RawItems processing logic forcibly sets the namespace, this is ineffective for cluster-scoped resources. Prior to version 0.13.0, tenant administrators can leverage the Controller's elevated privileges to create cluster-scoped resources (such as ClusterRole and ValidatingWebhookConfiguration) that they cannot create directly, achieving cross-tenant privilege escalation and cluster-level attacks. The attack vector has a few limiting factors. This attack requires Tenant Owner privileges and requires Capsule Controller running with cluster-admin privileges (default configuration). Additionally, some clusters may have additional admission controllers blocking malicious resources. Version 0.13.0 patches this issue. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-22872? +

CVE-2026-22872 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0043, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-22872? +

CVE-2026-22872 affects products from projectcapsule, specifically: capsule. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-22872? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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