How severe is CVE-2026-42876?

CVE-2026-42876 has a CVSS score of 4.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-42876?

CVE-2026-42876 affects the following packages: github.com/external-secrets/external-secrets/apis (Go). Ecosystems affected: Go.

How do I fix CVE-2026-42876?

Update github.com/external-secrets/external-secrets/apis to 2.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42876 is resolved across your whole dependency graph.

How do I detect CVE-2026-42876 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/external-secrets/external-secrets/apis, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-42876 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-42876 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-42876 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-42876?

CVE-2026-42876 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 12th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-42876?

CVE-2026-42876 is classified as CWE-285 (CWE-285). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-42876 published, and has it been updated?

CVE-2026-42876 was published on May 11, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2026-42876 — apis

MEDIUMFix: external-secrets/external-secrets@4ddd240

CVE-2026-42876 is a medium-severity (CVSS 4.9) CWE-285 vulnerability in github.com/external-secrets/external-secrets/apis. A fix is available for github.com/external-secrets/external-secrets/apis — see the affected versions and patch details below.

External Secrets Operator: Privilege escalation with secret overwriting

Also known asGHSA-fq7h-9x26-6j22GO-2026-5377

Published

May 11, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42876.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs12th percentile — riskier than 12% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/external-secrets/external-secrets/apis

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/external-secrets/external-secrets/apis`	≥ 0.1.0&&< 2.4.1	2.4.1`go get github.com/external-secrets/external-secrets/apis@v2.4.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/external-secrets/external-secrets/apis, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/external-secrets/external-secrets/apis to 2.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42876 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat rates this as MODERATE severity (CVSS 4.9). The External Secrets Operator vulnerability allows users with permission to create ExternalSecret resources to generate service account tokens within their namespace. Exploitation requires specific preconditions: the target namespace must contain misconfigured…

Workaround published by Red Hat

Update to External Secrets Operator version 2.4.1 or later. Workarounds include: (1) Add admission control logic to prevent ExternalSecret Templates targeting undesired secret Types; (2) Remove Service Account Token generation via kube-controller-manager flags; (3) Restrict User RBAC on production clusters and sensitive namespaces to limit who can create ExternalSecret resources.

Source: Red Hat security advisory for CVE-2026-42876 (CC BY 4.0)

Frequently Asked Questions

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 hav