What’s Vulnerable › Vulnerabilities

CVE-2026-110715: MuJS 1.3.6 before 1.3.9 Heap Out-of-Bounds Read/Write via Array.prototype.sort

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-14 · updated 2026-10-15
• Weakness: CWE-787

Description

MuJS 1.3.6 before 1.3.9 contains a heap out-of-bounds read and write vulnerability in Array.prototype.sort that allows attackers to corrupt memory by inflating a simple array's length. Attackers can supply JavaScript that enlarges a dense array's length and calls sort, causing Ap_sort_cmp and Ap_sort_swap to access slots past the buffer and crash the process.

Affected products

• Artifex Software MuJS: from 1.3.6 before 1.3.9 — fixed in 1.3.9

How to fix

Upgrade to a fixed version: Artifex Software MuJS 1.3.9. Check the vendor advisory for mitigations.

References

• https://codeberg.org/ccxvii/mujs
• https://codeberg.org/ccxvii/mujs/commit/32064e10caa45e68fc87331ca53d042049cc9396
• https://codeberg.org/ccxvii/mujs/src/commit/307f18c4216420f2f56e22d8e7040baa39a6304a/jsarray.c#L245
• https://hackmd.io/@haind-pwn/mujs-array-length-flat-oob
• https://mujs.com/downloads/
• https://www.vulncheck.com/advisories/mujs-1.3.6-before-1.3.9-heap-out-of-bounds-read-write-via-array-prototype-sort

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