CVE-2021-25743: K8s.io/kubernetes Kubectl ANSI Escape Characters Not Vulnerability

LOW
Advisory Identifier: GHSA-f9jg-8p32-2f55
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CVSS 3.0
CWE-150
Published
Advisory Summary

CVE-2021-25743 is a LOW (CVSS 3.0) kubectl ansi escape characters not vulnerability (CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences) affecting K8s.io/kubernetes libraries in the Go ecosystem. The issue involves kubectl ansi escape characters not filtered. Remediation is available by upgrading affected packages to version 1.26.0-alpha.3.

CVE-2021-25743 at a Glance

CVE Identifier CVE-2021-25743
GHSA Identifier GHSA-f9jg-8p32-2f55
Severity LOW
CVSS v3.1 Base Score 3.0
CWE Classification CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences
Affected Product K8s.io/kubernetes
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 3.0

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

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

How to Fix CVE-2021-25743

To remediate this vulnerability, upgrade all affected K8s.io/kubernetes 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/kubernetes fixed: 1.26.0-alpha.3 
Upgrade k8s.io/kubernetes to 1.26.0-alpha.3
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/kubernetes

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-25743, inspect your project dependencies for K8s.io/kubernetes:

inspect dependencies for k8s.io/kubernetes

Analyze the terminal output to locate any version of K8s.io/kubernetes in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.26.0-alpha.3), 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-150: Improper Neutralization of Escape, Meta, or Control Sequences, where the product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component. In K8s.io/kubernetes, 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

kubectl (k8s.io/kubernetes/pkg/kubectl) does not neutralize escape, meta or control sequences contained in the raw data it outputs to a terminal. This includes but is not limited to the unstructured string fields in objects such as Events.

CVE-2021-25743 Affected K8s.io/kubernetes Versions

1 component(s)
Fixed Versions:
1.26.0-alpha.3
Product / Package Ecosystem Affected Versions Fixed Version
k8s.io/kubernetes
golang/k8s.io/kubernetes
Go
< 1.26.0-alpha.3
1.26.0-alpha.3

References

NVD — CVE-2021-25743 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-25743
K8s.io/kubernetes Source Repository REPOSITORY
https://github.com/kubernetes/kubernetes/issues/101695
K8s.io/kubernetes Source Repository REPOSITORY
https://github.com/kubernetes/kubernetes/pull/112553
Security Fix Commit FIX COMMIT
https://github.com/kubernetes/kubernetes/commit/dad0e937c0f76344363eb691b2668490ffef8537
K8s.io/kubernetes Source Repository REPOSITORY
https://github.com/kubernetes/kubernetes
K8s.io/kubernetes Security Information SECURITY
https://security.netapp.com/advisory/ntap-20220217-0003

Frequently Asked Questions

What is CVE-2021-25743?
CVE-2021-25743 is a security vulnerability in K8s.io/kubernetes involving kubectl ANSI escape characters not filtered under CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences.
Which K8s.io/kubernetes versions are affected?
Affected versions include releases prior to 1.26.0-alpha.3 across affected packages: k8s.io/kubernetes.
What version fixes CVE-2021-25743?
Upgrading to 1.26.0-alpha.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is k8s.io/kubernetes affected?
Yes, k8s.io/kubernetes is affected in releases prior to 1.26.0-alpha.3. Upgrade your dependency to 1.26.0-alpha.3 or later.
What is the CVSS score of CVE-2021-25743?
CVE-2021-25743 has a CVSS v3.1 base score of 3.0 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:N.
What CWE is associated with CVE-2021-25743?
CVE-2021-25743 is classified under CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences (The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as escape, meta, or control character sequences when they are sent to a downstream component.).
How can I check Go dependencies for CVE-2021-25743?
Run the dependency tree command: 'inspect dependencies for k8s.io/kubernetes'. 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-f9jg-8p32-2f55",
  "modified" : "2023-10-02T15:53:13Z",
  "published" : "2022-01-08T00:00:21Z",
  "aliases" : [ "CVE-2021-25743" ],
  "summary" : "kubectl ANSI escape characters not filtered",
  "details" : "kubectl (k8s.io/kubernetes/pkg/kubectl) does not neutralize escape, meta or control sequences contained in the raw data it outputs to a terminal. This includes but is not limited to the unstructured string fields in objects such as Events.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "k8s.io/kubernetes"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.26.0-alpha.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-25743"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/kubernetes/issues/101695"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/kubernetes/pull/112553"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/kubernetes/kubernetes/commit/dad0e937c0f76344363eb691b2668490ffef8537"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/kubernetes/kubernetes"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20220217-0003"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-150" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-09-07T23:58:59Z",
    "nvd_published_at" : "2022-01-07T00:15:00Z"
  }
}