CVE-2026-4342: K8s.io/ingress nginx Ingress-nginx Comment-based Nginx Configuration Injection Vulnerability

HIGH
Advisory Identifier: GHSA-f53h-mxv9-cp98
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CVSS 8.8
CWE-20
Published
Advisory Summary

CVE-2026-4342 is a HIGH (CVSS 8.8) ingress-nginx comment-based nginx configuration injection vulnerability (CWE-20: Improper Input Validation) affecting K8s.io/ingress nginx libraries in the Go ecosystem. The issue involves ingress-nginx comment-based nginx configuration injection. Remediation is available by upgrading affected packages to version 0.0.0-20260319175635-5183b7d86137.

CVE-2026-4342 at a Glance

CVE Identifier CVE-2026-4342
GHSA Identifier GHSA-f53h-mxv9-cp98
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-20: Improper Input Validation
Affected Product K8s.io/ingress nginx
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 8.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-4342

To remediate this vulnerability, upgrade all affected K8s.io/ingress nginx dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

k8s.io/ingress-nginx fixed: 0.0.0-20260319175635-5183b7d86137 
Upgrade k8s.io/ingress-nginx to 0.0.0-20260319175635-5183b7d86137
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for k8s.io/ingress-nginx

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-4342, inspect your project dependencies for K8s.io/ingress nginx:

inspect dependencies for k8s.io/ingress-nginx

Analyze the terminal output to locate any version of K8s.io/ingress nginx in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.0.0-20260319175635-5183b7d86137), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In K8s.io/ingress nginx, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A security issue was discovered in ingress-nginx where a combination of Ingress annotations can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

CVE-2026-4342 Affected K8s.io/ingress nginx Versions

1 component(s)
Fixed Versions:
0.0.0-20260319175635-5183b7d86137
Product / Package Ecosystem Affected Versions Fixed Version
k8s.io/ingress-nginx
golang/k8s.io/ingress-nginx
Go
< 0.0.0-20260319175635-5183b7d86137
0.0.0-20260319175635-5183b7d86137

References

NVD — CVE-2026-4342 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4342
K8s.io/ingress nginx Source Repository REPOSITORY
https://github.com/kubernetes/kubernetes/issues/137893
Security Fix Commit FIX COMMIT
https://github.com/kubernetes/ingress-nginx/commit/5183b7d861377a9a2f6d2acaf44f8f6abd5cd0aa
K8s.io/ingress nginx Source Repository REPOSITORY
https://github.com/kubernetes/ingress-nginx
K8s.io/ingress nginx Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/03/19/9

Frequently Asked Questions

What is CVE-2026-4342?
CVE-2026-4342 is a security vulnerability in K8s.io/ingress nginx involving ingress-nginx comment-based nginx configuration injection under CWE-20: Improper Input Validation.
Which K8s.io/ingress nginx versions are affected?
Affected versions include releases prior to 0.0.0-20260319175635-5183b7d86137 across affected packages: k8s.io/ingress-nginx.
What version fixes CVE-2026-4342?
Upgrading to 0.0.0-20260319175635-5183b7d86137 (or the latest patched release for your respective branch) resolves the vulnerability.
Is k8s.io/ingress-nginx affected?
Yes, k8s.io/ingress-nginx is affected in releases prior to 0.0.0-20260319175635-5183b7d86137. Upgrade your dependency to 0.0.0-20260319175635-5183b7d86137 or later.
What is the CVSS score of CVE-2026-4342?
CVE-2026-4342 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-4342?
CVE-2026-4342 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check Go dependencies for CVE-2026-4342?
Run the dependency tree command: 'inspect dependencies for k8s.io/ingress-nginx'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f53h-mxv9-cp98",
  "modified" : "2026-03-20T17:26:08Z",
  "published" : "2026-03-20T00:31:28Z",
  "aliases" : [ "CVE-2026-4342" ],
  "summary" : "ingress-nginx comment-based nginx configuration injection",
  "details" : "A security issue was discovered in ingress-nginx where a combination of Ingress annotations can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "k8s.io/ingress-nginx"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.0.0-20260319175635-5183b7d86137"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-4342"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/kubernetes/issues/137893"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/ingress-nginx/commit/5183b7d861377a9a2f6d2acaf44f8f6abd5cd0aa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/kubernetes/ingress-nginx"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/03/19/9"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-20T17:26:08Z",
    "nvd_published_at" : "2026-03-19T22:16:43Z"
  }
}