CVE-2021-21285Network attack vector

Daemon crash via unvalidated manifest layer digest

Published Feb 2, 2021 · Updated Aug 3, 2024

Denial of service in Moby before 19.03.15 and 20.0.0 through 20.10.2 allows remote attackers to crash dockerd via a malformed image manifest. The schema 1, schema 2, and BuildKit pull paths accept layer digests without calling Digest.Validate, allowing an invalid digest to reach code that terminates the daemon. A user with daemon access must initiate the image pull; the crash interrupts workloads managed by that daemon.

CVSS severity6.5
Medium
EPSS probability3.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Moby before 19.03.15 and 20.0.0 through 20.10.2 allows remote attackers to crash dockerd via a malformed image manifest. The schema 1, schema 2, and BuildKit pull paths accept layer digests without calling Digest.Validate, allowing an invalid digest to reach code that terminates the daemon. A user with daemon access must initiate the image pull; the crash interrupts workloads managed by that daemon.

The record

CVE
CVE-2021-21285
Published
Feb 2, 2021
Updated
Aug 3, 2024
Vendor
Moby Project
Product
Moby
Classifications
CWE-754, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 19.03.15
  2. Affected versionversion=>= 20.0.0, < 20.10.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Moby Project · Mobyversion=< 19.03.15; version=>= 20.0.0, < 20.10.3

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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