CVE-2026-93753Public exploitNetwork attack vectorHinoki check available

Inherited-property injection via target-dependent prototype guard

Published Sep 18, 2026 · Updated Sep 18, 2026

Prototype poisoning in TehShrike deepmerge 4.3.1 and earlier allows remote attackers to inject inherited values via crafted merge input. The mergeObject function uses propertyIsUnsafe to inspect the target's shape rather than rejecting dangerous key names, so proto assignment can set the returned object's prototype. Exploitation requires an application to merge attacker-controlled objects into a null-prototype target, a primitive or null placeholder, or a target with its own proto key; injected values then affect only code that trusts inherited properties.

CVSS severity8.7
High
EPSS probability0.51%
Next 30 days · Oct 20, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Prototype poisoning in TehShrike deepmerge 4.3.1 and earlier allows remote attackers to inject inherited values via crafted merge input. The mergeObject function uses propertyIsUnsafe to inspect the target's shape rather than rejecting dangerous key names, so proto assignment can set the returned object's prototype. Exploitation requires an application to merge attacker-controlled objects into a null-prototype target, a primitive or null placeholder, or a target with its own proto key; injected values then affect only code that trusts inherited properties.

The record

CVE
CVE-2026-93753
Published
Sep 18, 2026
Updated
Sep 18, 2026
Vendor
TehShrike
Product
deepmerge
Classifications
CWE-1321, T1565
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record 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 <=4.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TehShrike · deepmergeversion=0 <=4.3.1

Published CVSS scores

7.5VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.7VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 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')
T1565Data Manipulation

Public exploit references

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Technologies

Your stack

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