# CVE-2026-88362: MuJS numeric conversion overflow in jsR_isindex

Source: https://junglewise.ai/threats/cve-2026-88362-mujs-e892c9fdb-contains-an-incorrect-numeric-conversion  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-24. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88362 · Severity: high · CVSS 7.5 · Published 2026-09-24

MuJS is a lightweight JavaScript interpreter used in document processing and embedded systems. A vulnerability in array indexing allows an attacker to provide an excessively large number as an array index, causing undefined behavior in the C runtime that terminates the process. An attacker can exploit this via specially crafted JavaScript code to cause a denial of service.

Technologies: [Artifex Mujs](https://junglewise.ai/threats/technologies/mujs). Vendors: [Artifex](https://junglewise.ai/threats/vendors/artifex).

## Quick answers

**Is CVE-2026-88362 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88362 being exploited in the wild.

**How severe is CVE-2026-88362?** High severity, with a CVSS score of 7.5, published 24 September 2026.

**Which products and versions are affected?** Artifex Mujs commit e892c9fdb and affected prior versions.

**Is there a fix for CVE-2026-88362?** A patch was published on 2026-08-19: Fix committed in 8a32c397b28fe45747ac4e9e4f3dca049825eda7 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-88362 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-88362?** Check whether you run Artifex Mujs at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The jsR_isindex() function in jsrun.c performs an implicit cast of a double-precision floating-point value to a 32-bit signed integer without range validation. When the double value exceeds INT_MAX or is negative, the conversion is undefined behavior in C. An attacker provides malicious JavaScript code (e.g., array access with index 2222222222222222) to trigger out-of-range conversion. The fix adds explicit range checking before the cast.

## Affected products

- Artifex MuJS commit e892c9fdb and affected prior versions

## Timeline

- 2026-08-07: disclosed
- 2026-08-19: patched: Fix committed in 8a32c397b28fe45747ac4e9e4f3dca049825eda7
- 2026-09-24: advisory

## References

- [https://bugs.ghostscript.com/show_bug.cgi?id=709636](https://bugs.ghostscript.com/show_bug.cgi?id=709636)
- [https://cgit.ghostscript.com/cgi-bin/cgit.cgi/mujs.git/commit/?id=8a32c397b28fe45747ac4e9e4f3dca049825eda7](https://cgit.ghostscript.com/cgi-bin/cgit.cgi/mujs.git/commit/?id=8a32c397b28fe45747ac4e9e4f3dca049825eda7)

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