CVE-2026-8657Public exploitNetwork attack vector

Object prototype modification via unsafe patch traversal

Published May 16, 2026 · Updated May 16, 2026

Prototype pollution in jsondiffpatch before 0.7.6 allows remote attackers to modify Object.prototype through crafted patch documents. The patch APIs traverse attacker-controlled delta keys and JSON Patch path segments into inherited constructor.prototype or proto properties without blocking unsafe names. Reachability requires a consuming application to pass attacker-controlled patch documents to an affected API; polluted properties can alter application behavior or cause a crash.

CVSS severity8.2
High
EPSS probability0.38%
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 jsondiffpatch before 0.7.6 allows remote attackers to modify Object.prototype through crafted patch documents. The patch APIs traverse attacker-controlled delta keys and JSON Patch path segments into inherited constructor.prototype or proto properties without blocking unsafe names. Reachability requires a consuming application to pass attacker-controlled patch documents to an affected API; polluted properties can alter application behavior or cause a crash.

The record

CVE
CVE-2026-8657
Published
May 16, 2026
Updated
May 16, 2026
Vendor
Benjamín Eidelman
Product
jsondiffpatch
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 16, 2026CVE publishedPublication date reported by the CVE source.
  2. May 16, 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 <0.7.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Benjamín Eidelman · jsondiffpatchversion=0 <0.7.6

Published CVSS scores

8.2SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
7.8SnykCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E: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.

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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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