CVE-2026-42876: External Secrets Operator privilege escalation via Service Account token injection

CVE-2026-42876 · Severity: medium · CVSS 4.9 · Published 2026-05-11

ExternalSecrets is a Kubernetes operator that integrates external secret management systems like AWS Secrets Manager or HashiCorp Vault with Kubernetes. A vulnerability allows users with limited permissions to trick the operator into creating long-lived authentication tokens for other service accounts. This could allow an attacker to impersonate more privileged accounts within the same namespace, potentially leading to unauthorized access to sensitive data or operations.

Technologies: External Secrets Operator. Vendors: External Secrets Operator, Go.

Quick answers

Is CVE-2026-42876 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42876 being exploited in the wild.
How severe is CVE-2026-42876?
Medium severity, with a CVSS score of 4.9, published 11 May 2026.
Which products and versions are affected?
External Secrets Operator >= 0.1.0, < 2.4.1, >0.1.0, <2.4.1; github.com/external-secrets/external-secrets/apis (Go) >= 0.1.0, < 2.4.1, SEMVER:introduced=0, SEMVER:introduced=0.1.0,fixed=2.4.1.
Is there a fix for CVE-2026-42876?
Yes. github.com/external-secrets/external-secrets/apis (Go): upgrade to 2.4.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-42876 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-42876?
Check whether you run External Secrets Operator or github.com/external-secrets/external-secrets/apis (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/external-secrets/external-secrets/apis (Go): upgrade to 2.4.1 or later
    go get github.com/external-secrets/external-secrets/apis@v2.4.1

Technical details

An authorization bypass exists in ExternalSecrets where a user with permission to create ExternalSecret resources can manipulate templates to target specific secret types. By crafting a template that targets the Service Account token secret type, the operator can be forced to create a Secret that Kubernetes automatically populates with a long-lived token for a specified service account. This allows for service account impersonation without the attacker having direct 'TokenRequest' or 'Secret' creation permissions. The vulnerability is mitigated by the requirement that the attacker must already have significant permissions within the namespace and that the target Service Account must be misconfigured. The issue is fixed in version 2.4.1 by disallowing these template combinations.

Affected products

  • ExternalSecrets ExternalSecrets >= 0.1.0, < 2.4.1

Identifiers

  • CVE-2026-42876
  • GHSA-fq7h-9x26-6j22
  • GO-2026-5377

Timeline

  • 2026-05-05: disclosed
  • 2026-05-08: advisory
  • 2026-05-08: patched: Fixed in version 2.4.1

References

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