CVE-2021-25745: K8s.io/ingress nginx Improper Input Validation Vulnerability

HIGH
Advisory Identifier: GHSA-pvmg-xgmx-9mxh
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CVSS 8.1
CWE-20
Published
Advisory Summary

CVE-2021-25745 is a HIGH (CVSS 8.1) improper input validation vulnerability (CWE-20: Improper Input Validation) affecting K8s.io/ingress nginx libraries in the Go ecosystem. The issue involves improper input validation in k8s.io/ingress-nginx. Remediation is available by upgrading affected packages to version 1.2.0.

CVE-2021-25745 at a Glance

CVE Identifier CVE-2021-25745
GHSA Identifier GHSA-pvmg-xgmx-9mxh
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification CWE-20: Improper Input Validation
Affected Product K8s.io/ingress nginx
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 8.1

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:N).

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 None (A:N)

How to Fix CVE-2021-25745

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: 1.2.0 
Upgrade k8s.io/ingress-nginx to 1.2.0
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-2021-25745, 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 1.2.0), 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 user that can create or update ingress objects can use the spec.rules[].http.paths[].path field of an Ingress object (in the networking.k8s.io or extensions API group) to obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.

CVE-2021-25745 Affected K8s.io/ingress nginx Versions

1 component(s)
Fixed Versions:
1.2.0
Product / Package Ecosystem Affected Versions Fixed Version
k8s.io/ingress-nginx
golang/k8s.io/ingress-nginx
Go
< 1.2.0
1.2.0

References

NVD — CVE-2021-25745 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-25745
K8s.io/ingress nginx Source Repository REPOSITORY
https://github.com/kubernetes/ingress-nginx/issues/8502
K8s.io/ingress nginx Source Repository REPOSITORY
https://github.com/kubernetes/ingress-nginx
K8s.io/ingress nginx Security Information SECURITY
https://groups.google.com/g/kubernetes-security-announce/c/7vQrpDZeBlc
K8s.io/ingress nginx Security Information SECURITY
https://security.netapp.com/advisory/ntap-20220609-0006

Frequently Asked Questions

What is CVE-2021-25745?
CVE-2021-25745 is a security vulnerability in K8s.io/ingress nginx involving Improper Input Validation in k8s.io/ingress-nginx under CWE-20: Improper Input Validation.
Which K8s.io/ingress nginx versions are affected?
Affected versions include releases prior to 1.2.0 across affected packages: k8s.io/ingress-nginx.
What version fixes CVE-2021-25745?
Upgrading to 1.2.0 (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 1.2.0. Upgrade your dependency to 1.2.0 or later.
What is the CVSS score of CVE-2021-25745?
CVE-2021-25745 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2021-25745?
CVE-2021-25745 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-2021-25745?
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-pvmg-xgmx-9mxh",
  "modified" : "2022-05-25T19:29:51Z",
  "published" : "2022-05-07T00:00:49Z",
  "aliases" : [ "CVE-2021-25745" ],
  "summary" : "Improper Input Validation in k8s.io/ingress-nginx",
  "details" : "A security issue was discovered in ingress-nginx where a user that can create or update ingress objects can use the spec.rules[].http.paths[].path field of an Ingress object (in the networking.k8s.io or extensions API group) to obtain the credentials of the ingress-nginx controller. In the default configuration, that credential has access to all secrets in the cluster.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "k8s.io/ingress-nginx"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-25745"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/ingress-nginx/issues/8502"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/kubernetes/ingress-nginx"
  }, {
    "type" : "WEB",
    "url" : "https://groups.google.com/g/kubernetes-security-announce/c/7vQrpDZeBlc"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20220609-0006"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-05-25T19:29:51Z",
    "nvd_published_at" : "2022-05-06T01:15:00Z"
  }
}