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

Quick assessment

Affected
projectcapsule capsule
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Capsule 是一个用于 Kubernetes 的多租户策略框架。在 0.13.0 至 0.13.7 版本中， 中的 函数错误地交换了新旧 Tenant 参数，导致校验的是旧的 值，而非用户提交的新值。因此，集群管理员可以在 Webhook 基于旧的有效状态接受更新后，存储一个格式错误的 。 随后，当该租户创建或更新 Ingress 时，流程会到达 ，该文件会评估这个格式错误的正则表达式模式，并忽略由此产生的正则表达式错误，进而将所有主机名视为“未匹配”，从而阻止受影响租户的 Ingress 操作，直到管理员修复

CVSS 6.8 · Medium EPSS 0.59% · P48

Affected Version Matrix 1

VendorProduct Version RangeStatus
projectcapsule capsule >= 0.13.0, < 0.13.7 affected
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I. Basic Information for CVE-2026-61795

Vulnerability Information
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Vulnerability Title
Capsule: hostnameRegexHandler.OnUpdate validates stale (old) Tenant regex, allowing invalid AllowedHostnames regex to bypass webhook validation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不充分的比较
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
projectcapsule capsule >= 0.13.0, < 0.13.7 -

II. Public POCs for CVE-2026-61795

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III. Intelligence Information for CVE-2026-61795

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Patches & Fixes for CVE-2026-61795 (1)

Other References for CVE-2026-61795 (2)

Same Patch Batch · projectcapsule · 2026-09-18 · 3 CVEs total

CVE-2026-61672 7.1 HIGH Capsule: Tenant owner bypasses Capsule's forbidden namespace/service/node label and annota
CVE-2026-61794 6.8 MEDIUM Capsule: Malformed ForbiddenAnnotations.Regex can bypass Tenant validation and trigger nam

IV. Related Vulnerabilities

Same product: capsule
Same vendor: projectcapsule
Same weakness: CWE-697