CVE-2021-25948Public exploitNetwork attack vector

Service interruption via unsafe prototype-key traversal

Published Jun 10, 2021 · Updated Aug 3, 2024

Prototype pollution in doowb expand-hash 0.1.0 through 1.0.1 allows attackers to interrupt a consuming service via crafted keys. The set function splits each property name on dots and follows obj[key] without rejecting proto, constructor, or prototype segments, allowing an inherited prototype object to become the assignment target. Exploitation requires an application to pass attacker-controlled object keys into the library; polluted properties can trigger exceptions that interrupt service or reach code execution when a separate executable gadget consumes them.

CVSS severity9.8
Critical
EPSS probability3.30%
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 doowb expand-hash 0.1.0 through 1.0.1 allows attackers to interrupt a consuming service via crafted keys. The set function splits each property name on dots and follows obj[key] without rejecting proto, constructor, or prototype segments, allowing an inherited prototype object to become the assignment target. Exploitation requires an application to pass attacker-controlled object keys into the library; polluted properties can trigger exceptions that interrupt service or reach code execution when a separate executable gadget consumes them.

The record

CVE
CVE-2021-25948
Published
Jun 10, 2021
Updated
Aug 3, 2024
Vendor
doowb
Product
expand-hash
Classifications
CWE-1321, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 10, 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=0.1.0, 0.1.1, 0.2.1, 0.2.2, 1.0.0, 1.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

doowb · expand-hashversion=0.1.0, 0.1.1, 0.2.1, 0.2.2, 1.0.0, 1.0.1

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/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 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')
T1499Endpoint Denial of Service

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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