Vulnerability Monitor

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CVE-2021-21284


In Docker before versions 9.03.15, 20.10.3 there is a vulnerability involving the --userns-remap option in which access to remapped root allows privilege escalation to real root. When using "--userns-remap", if the root user in the remapped namespace has access to the host filesystem they can modify files under "/var/lib/docker/<remapping>" that cause writing files with extended privileges. Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.8, indicating it requires adjacent network access with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts integrity (unauthorized modifications), for affected systems. Impacting 3 products from docker, from debian, from netapp organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-02-02T18:15:11.827

Last Modified

2024-11-21T05:47:55.867

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 6.8 (MEDIUM)

CVSSv2 Vector

AV:A/AC:L/Au:S/C:N/I:P/A:N

  • Access Vector: ADJACENT_NETWORK
  • Access Complexity: LOW
  • Authentication: SINGLE
  • Confidentiality Impact: NONE
  • Integrity Impact: PARTIAL
  • Availability Impact: NONE
Exploitability Score

5.1

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-22
  • Type: Primary
    CWE-22

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application docker docker < 19.03.15 Yes
Application docker docker < 20.10.3 Yes
Operating System debian debian_linux 10.0 Yes
Application netapp e-series_santricity_os_controller ≤ 11.60.3 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For docker's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.