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ExternalSecrets vulnerable to privilege escalation with secret overwriting

Moderate severity GitHub Reviewed Published May 5, 2026 in external-secrets/external-secrets • Updated May 13, 2026

Package

gomod github.com/external-secrets/external-secrets/apis (Go)

Affected versions

>= 0.1.0, < 2.4.1

Patched versions

2.4.1

Description

ExternalSecrets allows users to craft Service Account tokens for misconfigured Service Accounts in namespaces the users have access to.

Impact

A user who only has permission to create ExternalSecret resources can cause the operator to create a Secret that Kubernetes will automatically populate with a long-lived token for the sepcified service account. This effectively allows the user to impersonate any service account in the namespace without needing direct create permissions on TokenRequest or Secrets of that type.

The problem is mitigated in severity by the fact that the user must have pre-existing permissions already at almost the same level as the escalation later gives. The attacker cannot use this method to gain access to more information without other things also being misconfigured in the ESO installation.

Patches

Disallow this combination including the bootstrap token secret type.

Workarounds

  • Add admission control logic to prevent the use of Templates targeting undesired Types
  • Remove Service Account Token generation via kube-controller-manager flags
  • Restrict User RBAC on production clusters and sensitive namespaces

References

@Skarlso Skarlso published to external-secrets/external-secrets May 5, 2026
Published to the GitHub Advisory Database May 8, 2026
Reviewed May 8, 2026
Published by the National Vulnerability Database May 11, 2026
Last updated May 13, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(1st percentile)

Weaknesses

Improper Authorization

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

CVE ID

CVE-2026-42876

GHSA ID

GHSA-fq7h-9x26-6j22

Source code

Credits

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