CVE-2026-8657: Jsondiffpatch Jsondiffpatch Patch APIs Are Vulnerable Vulnerability

HIGH
Advisory Identifier: GHSA-j4fx-xxwh-2485
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CVSS 8.2
CWE-1321
Published
Advisory Summary

CVE-2026-8657 is a HIGH (CVSS 8.2) jsondiffpatch patch apis are vulnerable vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting Jsondiffpatch libraries in the npm ecosystem. The issue involves jsondiffpatch patch apis are vulnerable to prototype pollution. Remediation is available by upgrading affected packages to version 0.7.6.

CVE-2026-8657 at a Glance

CVE Identifier CVE-2026-8657
GHSA Identifier GHSA-j4fx-xxwh-2485
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product Jsondiffpatch
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-8657

To remediate this vulnerability, upgrade all affected Jsondiffpatch dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

jsondiffpatch fixed: 0.7.6 
npm install jsondiffpatch@0.7.6
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls jsondiffpatch

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-8657, inspect your project dependencies using npm:

npm ls jsondiffpatch

Analyze the terminal output to locate any version of Jsondiffpatch in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.7.6), your application is affected.

Note: The npm ls jsondiffpatch command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. In Jsondiffpatch, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Versions of the package jsondiffpatch before 0.7.6 are vulnerable to Prototype Pollution via the jsondiffpatch.patch() and jsondiffpatch/formatters/jsonpatch.patch() APIs. An attacker can perform prototype pollution by supplying crafted delta or JSON Patch documents, as attacker-controlled property names and path segments are used to traverse and modify objects without restricting access to special properties like __proto__ or constructor.prototype, allowing modification of Object.prototype.

CVE-2026-8657 Affected Jsondiffpatch Versions

1 component(s)
Fixed Versions:
0.7.6
Product / Package Ecosystem Affected Versions Fixed Version
jsondiffpatch
npm/jsondiffpatch
npm
< 0.7.6
0.7.6

References

NVD — CVE-2026-8657 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-8657
Security Fix Commit FIX COMMIT
https://github.com/benjamine/jsondiffpatch/commit/381c0125efab49f6f0dbc08317d01d55717672af
Jsondiffpatch Source Repository REPOSITORY
https://gist.github.com/yuki-matsuhashi/e570fb1579ae1f3190059b622b0473fb
Jsondiffpatch Source Repository REPOSITORY
https://github.com/benjamine/jsondiffpatch
Jsondiffpatch Source Repository REPOSITORY
https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/filters/nested.ts%23L107-L115
Jsondiffpatch Source Repository REPOSITORY
https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/filters/nested.ts%23L82-L87
Jsondiffpatch Source Repository REPOSITORY
https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/formatters/jsonpatch-apply.ts%23L146-L168
Jsondiffpatch Source Repository REPOSITORY
https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/formatters/jsonpatch-apply.ts%23L171-L199
Jsondiffpatch Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-16732792
Jsondiffpatch Security Information SECURITY
https://security.snyk.io/vuln/SNYK-JS-JSONDIFFPATCH-16322990

Frequently Asked Questions

What is CVE-2026-8657?
CVE-2026-8657 is a security vulnerability in Jsondiffpatch involving jsondiffpatch patch APIs are vulnerable to prototype pollution under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which Jsondiffpatch versions are affected?
Affected versions include releases prior to 0.7.6 across affected packages: jsondiffpatch.
What version fixes CVE-2026-8657?
Upgrading to 0.7.6 (or the latest patched release for your respective branch) resolves the vulnerability.
Is jsondiffpatch affected?
Yes, jsondiffpatch is affected in releases prior to 0.7.6. Upgrade your dependency to 0.7.6 or later.
What is the CVSS score of CVE-2026-8657?
CVE-2026-8657 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L.
What CWE is associated with CVE-2026-8657?
CVE-2026-8657 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-8657?
Run the dependency tree command: 'npm ls jsondiffpatch'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j4fx-xxwh-2485",
  "modified" : "2026-08-31T22:10:51Z",
  "published" : "2026-05-16T06:30:29Z",
  "aliases" : [ "CVE-2026-8657" ],
  "summary" : " jsondiffpatch patch APIs are vulnerable to prototype pollution",
  "details" : "Versions of the package jsondiffpatch before 0.7.6 are vulnerable to Prototype Pollution via the jsondiffpatch.patch() and jsondiffpatch/formatters/jsonpatch.patch() APIs. An attacker can perform prototype pollution by supplying crafted delta or JSON Patch documents, as attacker-controlled property names and path segments are used to traverse and modify objects without restricting access to special properties like __proto__ or constructor.prototype, allowing modification of Object.prototype.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS: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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "jsondiffpatch"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.7.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-8657"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/benjamine/jsondiffpatch/commit/381c0125efab49f6f0dbc08317d01d55717672af"
  }, {
    "type" : "WEB",
    "url" : "https://gist.github.com/yuki-matsuhashi/e570fb1579ae1f3190059b622b0473fb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/benjamine/jsondiffpatch"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/filters/nested.ts%23L107-L115"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/filters/nested.ts%23L82-L87"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/formatters/jsonpatch-apply.ts%23L146-L168"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/benjamine/jsondiffpatch/blob/96112c35a98f9201dd75d67fcee68a952c79e2fe/packages/jsondiffpatch/src/formatters/jsonpatch-apply.ts%23L171-L199"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-16732792"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-JS-JSONDIFFPATCH-16322990"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-31T22:10:51Z",
    "nvd_published_at" : "2026-05-16T06:16:18Z"
  }
}