CVE-2026-40897Public exploitNetwork attack vector

Code execution via unrestricted array property assignment

Published Apr 24, 2026 · Updated Apr 24, 2026

Arbitrary code execution in Jos de Jong Math.js 13.1.1 through 15.1.1 allows remote authenticated users to run JavaScript via expressions. The expression parser's setSafeProperty accepted arbitrary named properties on arrays, letting a crafted expression replace map and reach Function.constructor through reviver-created nodes. Exposure requires an application to evaluate attacker-controlled expressions; successful execution runs with the privileges and data access of its JavaScript process.

CVSS severity8.8
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary code execution in Jos de Jong Math.js 13.1.1 through 15.1.1 allows remote authenticated users to run JavaScript via expressions. The expression parser's setSafeProperty accepted arbitrary named properties on arrays, letting a crafted expression replace map and reach Function.constructor through reviver-created nodes. Exposure requires an application to evaluate attacker-controlled expressions; successful execution runs with the privileges and data access of its JavaScript process.

The record

CVE
CVE-2026-40897
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
Jos de Jong
Product
Math.js
Classifications
CWE-915, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 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=>= 13.1.1, < 15.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Jos de Jong · Math.jsversion=>= 13.1.1, < 15.2.0

Published CVSS scores

8.8GitHubCVSS:3.0/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-915Improperly Controlled Modification of Dynamically-Determined Object Attributes
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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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