CVE-2021-21284

lowpriority · track · 27EPSS 0.011 · 65 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.06% (65th) EPSS
CVSS 2.7 · low
Is it mine?
25 products
Check your exposure
Who says so?
6 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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.

01

cvss

Technical severity, 0–10. One row per scoring source.

6.8
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.7–6.8

v2.02.7lowAV:A/AC:L/Au:S/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 5.1 · impact 2.9
v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 2.3 · impact 4
v3.16.8mediumAV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:Nsecondary · FSTEC (BDU) RU
v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:Nsecondary · ENISA EU
v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:Nsecondary · security-advisories@github.comexploitability 2.3 · impact 4
v3.16.8mediumCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:Nsecondary · OSV
v3.16.2mediumCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)
02

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-22USprimaryCWE-22USCWE-22US
03

affected products (25)

Products and version ranges known to be affected.

showing 20 of 25
04

advisories (2)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2023-2716docker: Mehrere SchwachstellenDeutsch2021-02-02csaf · cert_bundDE

    Ein entfernter, authentisierter Angreifer kann mehrere Schwachstellen in docker ausnutzen, um seine Privilegien zu erhöhen und um einen Denial of Service Angriff durchzuführen.

  • GHSA-7452-xqpj-6rpcmoby Access to remapped root allows privilege escalation to real root2024-01-31ghsa · osvUS

    ### Impact 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. ### Patches Versions 20.10.3 and 19.03.15 contain patches that prevent privilege escalation from remapped user. ### Credits Maintainers would like to thank Alex Chapman for discovering the vulnerability; @awprice, @nathanburrell, @raulgomis, @chris-walz, @erin-jensby, @bassmatt, @mark-adams, @dbaxa for working on it and Zac Ellis for responsibly disclosing it to security@docker.com

05

also known as (4)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundnvdosvNVDCVE.orgMITRE
published 2021-02-02modified 2026-06-17
08

references (43)

External citations — patches, advisories, analysis.

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