Kyverno resource with a deletionTimestamp may allow policy circumvention

Description

Impact

In versions of Kyverno prior to 1.10.0, resources which have the deletionTimestamp field defined can bypass validate, generate, or mutate-existing policies, even in cases where the validationFailureAction field is set to Enforce.

This situation occurs as resources pending deletion were being consciously exempted by Kyverno, as a way to reduce processing load as policies are typically not applied to objects which are being deleted.

However, this could potentially result in allowing a malicious user to leverage the Kubernetes finalizers feature by setting a finalizer which causes the Kubernetes API server to set the deletionTimestamp and then not completing the delete operation as a way to explicitly to bypass a Kyverno policy.

Note that this is not applicable to Kubernetes Pods but, as an example, a Kubernetes Service resource can be manipulated using an indefinite finalizer to bypass policies.

Patches

This is resolved in Kyverno 1.10.0.

Workarounds

There is no known workaround.

References

Are there any links users can visit to find out more?

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2023-06-05 17:10:13 UTC
Updated
2023-11-11 05:00:48 UTC
GitHub reviewed
2023-06-05 17:10:13 UTC
NVD published
2023-06-01

EPSS Score

Score Percentile
0.05% 16.80%

CVSS Scores

Base score Version Severity Vector
6.5 3.1
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-285 Improper Authorization

Credits

  • bburky (finder)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/kyverno/kyverno < 1.10.0 1.10.0

References

cvelogic Threat Intelligence