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Vulnerability · Published Sep 18, 2026 · Assigned by GitHub_M

CVE-2026-61795Capsule: hostnameRegexHandler.OnUpdate validates stale (old) Tenant regex, allowing invalid AllowedHostnames regex to bypass webhook validation

Medium 6.8

In plain English

A medium-severity security flaw in capsule from projectcapsule. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.8Medium
Exploit odds (30 days)0.6%top 51.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.7, hostnameRegexHandler.OnUpdate in internal/webhook/tenant/validation/hostname_regex.go reverses the new and old Tenant parameters and validates the previous AllowedHostnames.Regex instead of the submitted value. A cluster administrator can therefore store a malformed AllowedHostnames.Regex after the webhook accepts the update based on stale valid state. Subsequent Ingress creation or update reaches validate_hostnames.go, which evaluates the malformed pattern, ignores the regular-expression error, and treats every hostname as unmatched, blocking Ingress operations for the affected tenant until an administrator repairs the Tenant configuration. This issue is fixed in version 0.13.7.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/projectcapsule/capsule0.13.7GHSA-f94q-w3w8-cj67
Gogithub.com/projectcapsule/capsule0.13.7GO-2026-6519

Affected products (as reported)

VendorProductVersions
projectcapsule capsule >= 0.13.0, < 0.13.7

Weakness: CWE-697 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

References