CVE-2021-31938

Privilege escalation via writable installed binaries

Published Jun 8, 2021 · Updated Aug 3, 2024

Elevation of privilege in Microsoft Kubernetes Tools before 1.3.1 allows local users to gain higher privileges through installed binaries. The extension's dependency installer leaves downloaded executables with write permissions that let a lower-privileged user replace them before later execution. Exploitation requires local low-privileged access and subsequent user interaction that runs a replaced binary at the victim's privilege level.

CVSS severity7.3
High
EPSS probability2.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Elevation of privilege in Microsoft Kubernetes Tools before 1.3.1 allows local users to gain higher privileges through installed binaries. The extension's dependency installer leaves downloaded executables with write permissions that let a lower-privileged user replace them before later execution. Exploitation requires local low-privileged access and subsequent user interaction that runs a replaced binary at the victim's privilege level.

The record

CVE
CVE-2021-31938
Published
Jun 8, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Kubernetes Tools
Classifications
T1574.005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <1.3.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Kubernetes Toolsversion=1.0.0 <1.3.1

Published CVSS scores

7.8National Institute of Standards and TechnologyCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.3Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1574.005Executable Installer File Permissions Weakness

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo