Internal response disclosure via webhook redirects
Published Sep 20, 2021 · Updated Jun 1, 2026
Unintended proxying in Kubernetes kube-apiserver allows remote authenticated users to read internal responses via webhook redirects. The admission webhook HTTP client follows attacker-controlled redirects into private networks and logs returned bodies and headers at verbosity 10. Exploitation requires control of a mutating or validating webhook response, access to API-server logs, and enabled profiling to change verbosity dynamically.
Summary
What happened
Unintended proxying in Kubernetes kube-apiserver allows remote authenticated users to read internal responses via webhook redirects. The admission webhook HTTP client follows attacker-controlled redirects into private networks and logs returned bodies and headers at verbosity 10. Exploitation requires control of a mutating or validating webhook response, access to API-server logs, and enabled profiling to change verbosity dynamically.
The record
- CVE
- CVE-2020-8561
- Published
- Sep 20, 2021
- Updated
- Jun 1, 2026
- Vendor
- Kubernetes
- Product
- Kubernetes
- Classifications
- CWE-441
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 20, 2021CVE publishedPublication date reported by the CVE source.
- Jun 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <*
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What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
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Your stack
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