CVE-2021-25741

HIGH

Kubernetes < 1.19.14 - Unauthenticated Files or Directories Accessible via Subpath Volume Mounts

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 3 public exploits for CVE-2021-25741. PoCs published by Glutenfree69, cdxiaodong.

AI-analyzed exploit summary This repository contains a functional Zig-based exploit demonstrating CVE-2021-25741, a TOCTOU symlink race condition in Kubernetes kubelet's volume mounting. It includes detailed technical documentation and a working PoC that shows how concurrent symlink swaps bypass path validation between `lstat()` and `open()`.

Description

A security issue was discovered in Kubernetes where a user may be able to create a container with subpath volume mounts to access files & directories outside of the volume, including on the host filesystem.

Exploits (3)

nomisec WORKING POC
by Glutenfree69 · poc
https://github.com/Glutenfree69/ZigRaceExploit

This repository contains a functional Zig-based exploit demonstrating CVE-2021-25741, a TOCTOU symlink race condition in Kubernetes kubelet's volume mounting. It includes detailed technical documentation and a working PoC that shows how concurrent symlink swaps bypass path validation between `lstat()` and `open()`.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Moderate
Reliability
Racy
Target: Kubernetes kubelet
No auth needed
Prerequisites: Linux environment · Docker for execution
devstral-2 · analyzed Mar 17, 2026 Full analysis →
nomisec WORKING POC
by cdxiaodong · poc
https://github.com/cdxiaodong/CVE-2021-25741

This repository contains a functional exploit for CVE-2021-25741, a vulnerability in Kubernetes. The exploit uses a crafted YAML file (pod.yaml) and a shell script (run.sh) to trigger the vulnerability, likely involving a symlink attack to achieve container escape or privilege escalation.

Classification
Working Poc 90%
Attack Type
Lpe
Complexity
Moderate
Reliability
Reliable
Target: Kubernetes (specific version not explicitly stated)
No auth needed
Prerequisites: Access to a Kubernetes cluster with the ability to create pods
devstral-2 · analyzed Feb 18, 2026 Full analysis →
inthewild WORKING POC
poc
https://github.com/betep0k/cve-2021-25741

This repository contains a functional exploit for CVE-2021-25741, a Kubernetes vulnerability allowing node filesystem mount via a race condition in kubelet. The exploit includes a YAML pod configuration and a script to automate deployment and verification.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Moderate
Reliability
Racy
Target: Kubernetes kubelet (v1.22.0-1.22.1, v1.21.0-1.21.4, v1.20.0-1.20.10, <=v1.19.14)
Auth required
Prerequisites: Privileges to create new pods · Vulnerable kubelet version
devstral-2 · analyzed Feb 23, 2026 Full analysis →

References (3)

Core 3
Core References
Mitigation, Third Party Advisory x_refsource_misc
https://github.com/kubernetes/kubernetes/issues/104980
Third Party Advisory x_refsource_confirm
https://security.netapp.com/advisory/ntap-20211008-0006/

Scores

CVSS v3 8.8
EPSS 0.3304
EPSS Percentile 97.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-552 CWE-20
Status published
Products (2)
k8s.io/kubernetes 0 - 1.19.15Go
kubernetes/kubernetes < 1.19.14
Published Sep 20, 2021
Tracked Since Feb 18, 2026