CVE-2021-21284

Public on

Last Modified: UTC

Description

A flaw was found in the `userns-remap` feature of Docker. The root user in the remapped namespace can modify files under /var/lib/docker/<remapping>, leading to possible privilege escalation to the root user in the host. The highest threat from this vulnerability is to data integrity.

A flaw was found in the userns-remap feature of Docker. The root user in the remapped namespace can modify files under /var/lib/docker/, leading to possible privilege escalation to the root user in the host. The highest threat from this vulnerability is to data integrity.

Additional information

  • Bugzilla 1924740: docker: access to remapped root allows privilege escalation to real root
  • CWE-732: Incorrect Permission Assignment for Critical Resource
  • FAQ: Frequently asked questions about CVE-2021-21284

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

6

6.8

Attack Vector

Local

Adjacent Network

Attack Complexity

Low

Low

Privileges Required

High

Low

User Interaction

None

None

Scope

Changed

Changed

Confidentiality Impact

None

None

Integrity Impact

High

High

Availability Impact

None

None

CVSS v3 Vector

Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N

NVD: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

Understanding the Weakness (CWE)

CWE-732

Confidentiality

Technical Impact: Read Application Data; Read Files or Directories

An attacker may be able to read sensitive information from the associated resource, such as credentials or configuration information stored in a file.

Access Control

Technical Impact: Gain Privileges or Assume Identity

An attacker may be able to modify critical properties of the associated resource to gain privileges, such as replacing a world-writable executable with a Trojan horse.

Integrity,Other

Technical Impact: Modify Application Data; Other

An attacker may be able to destroy or corrupt critical data in the associated resource, such as deletion of records from a database.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

What can I do if my product is listed as "Will not fix"?

What can I do if my product is listed as "Fix deferred"?

What is a mitigation?

I have a Red Hat product but it is not in the above list, is it affected?

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

My product is listed as "Out of Support Scope". What does this mean?

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