What is the CVSS score of CVE-2021-21334?

CVE-2021-21334 has a CVSS 3.1 base score of 6.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N. EPSS exploitation probability: 2.0%.

Is there a patch available for CVE-2021-21334?

Yes, a patch is available for CVE-2021-21334. Update the affected software to the latest version immediately.

Containerd CVE-2021-21334

MEDIUM

Exposure of Resource to Wrong Sphere (CWE-668)

2021-03-10 security-advisories@github.com

Information Disclosure Kubernetes Fedora Containerd Linuxfoundation Fedoraproject

6.3

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-668 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V8 - Authorization Resource sphere isolation MITRE ATT&CK 1 technique across 1 tactic: Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 6.3 (MEDIUM). Attack characteristics: network attack vector, high complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could access resources from an unintended security context by sending crafted requests to the affected application.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 2.0% exploitation probability (EPSS)

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AnalysisAI

In containerd (an industry-standard container runtime) before versions 1.3.10 and 1.4.4, containers launched through containerd's CRI implementation (through Kubernetes, crictl, or any other. Rated medium severity (CVSS 6.3), this vulnerability is remotely exploitable. This Exposure of Resource to Wrong Sphere vulnerability could allow attackers to access resources from an unintended security context.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Implement proper access controls, validate resource access permissions, use security boundaries.

Affected Packages

go github.com/containerd/containerd fix: 1.3.10, 1.4.4

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in go

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Exposure of Resource to Wrong Sphere (CWE-668), which allows attackers to access resources from an unintended security context. In containerd (an industry-standard container runtime) before versions 1.3.10 and 1.4.4, containers launched through containerd's CRI implementation (through Kubernetes, crictl, or any other pod/container client that uses the containerd CRI service) that share the same image may receive incorrect environment variables, including values that are defined for other containers. If the affected containers have different security contexts, this may allow sensitive information to be unintentionally shared. If you are not using containerd's CRI implementation (through one of the mechanisms described above), you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image which have different environment variables, you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image in rapid succession, you have reduced likelihood of being vulnerable to this issue This vulnerability has been fixed in containerd 1.3.10 and containerd 1.4.4. Users should update to these versions. Affected products include: Linuxfoundation Containerd, Fedoraproject Fedora.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.3 MEDIUM

AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

None

Availability

None

DescriptionNVD

In containerd (an industry-standard container runtime) before versions 1.3.10 and 1.4.4, containers launched through containerd's CRI implementation (through Kubernetes, crictl, or any other pod/container client that uses the containerd CRI service) that share the same image may receive incorrect environment variables, including values that are defined for other containers. If the affected containers have different security contexts, this may allow sensitive information to be unintentionally shared. If you are not using containerd's CRI implementation (through one of the mechanisms described above), you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image which have different environment variables, you are not vulnerable to this issue. If you are not launching multiple containers or Kubernetes pods from the same image in rapid succession, you have reduced likelihood of being vulnerable to this issue This vulnerability has been fixed in containerd 1.3.10 and containerd 1.4.4. Users should update to these versions.

Threat Intelligence Overview

EPSS Score

2.0%

Top 21% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 2.0%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +2

CVSS: +32

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.