CVE-2021-25944Public exploitNetwork attack vector

Denial of service via unchecked recursive property assignment

Published May 25, 2021 · Updated Aug 3, 2024

Prototype pollution in d5 deep-defaults 1.0.0 through 1.0.5 allows remote attackers to disrupt service via crafted source objects. The _deepDefaults() function recursively assigns src properties without checking value types or requiring each key to be an own property, so a proto key modifies Object.prototype. Reachability depends on a consuming application passing attacker-controlled objects to the library; denial of service is application-dependent, and code execution requires a suitable gadget.

CVSS severity9.8
Critical
EPSS probability2.96%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in d5 deep-defaults 1.0.0 through 1.0.5 allows remote attackers to disrupt service via crafted source objects. The _deepDefaults() function recursively assigns src properties without checking value types or requiring each key to be an own property, so a proto key modifies Object.prototype. Reachability depends on a consuming application passing attacker-controlled objects to the library; denial of service is application-dependent, and code execution requires a suitable gadget.

The record

CVE
CVE-2021-25944
Published
May 25, 2021
Updated
Aug 3, 2024
Vendor
d5
Product
deep-defaults
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 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=1.0.5, 1.0.3, 1.0.2, 1.0.1, 1.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

d5 · deep-defaultsversion=1.0.5, 1.0.3, 1.0.2, 1.0.1, 1.0.0

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Public exploit references

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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