# CVE-2016-9109: Artifex Software MuJS out-of-bounds read in chartorune

Source: https://junglewise.ai/threats/cve-2016-9109-artifex-software-mujs-out-of-bounds-read-in-chartorune  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2017-01-18. Updated: 2026-05-13  
License: CC BY 4.0 with a link back

CVE-2016-9109 · Severity: high · CVSS 7.5 · Published 2017-01-18

MuJS, a lightweight JavaScript interpreter used in various applications, is vulnerable to a flaw that can cause the software to crash. By providing specially crafted JavaScript code containing incomplete escape sequences, an attacker can trigger a memory error that shuts down the service. This can lead to a denial-of-service condition, impacting the availability of applications that rely on this engine.

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

## Quick answers

**Is CVE-2016-9109 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2016-9109 being exploited in the wild.

**How severe is CVE-2016-9109?** High severity, with a CVSS score of 7.5, published 18 January 2017.

**Which products and versions are affected?** Artifex Software MuJS before commit a0ceaf5050faf419401fe1b83acfa950ec8a8a89.

**Is there a fix for CVE-2016-9109?** A patch was published on 2016-11-07: Fix identified in MuJS git repository Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2016-9109 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2016-9109?** Check whether you run Artifex Mujs. 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

An out-of-bounds (OOB) read vulnerability exists in MuJS within the `jsU_chartorune` function in `utf.c`. The issue stems from an incomplete fix for a previous vulnerability (CVE-2016-7563), where the lexer incorrectly handles multi-line comments or strings ending with specific characters like '*' or incomplete escape sequences. When the lexer encounters these sequences at the end of the input buffer, it may unconditionally attempt to read the next character, leading to a heap-buffer-overflow read. An unauthenticated remote attacker can exploit this by providing malicious JavaScript input, resulting in an application crash (Denial of Service). The vulnerability was addressed in commit a0ceaf5050faf419401fe1b83acfa950ec8a8a89.

## Affected products

- Artifex Software MuJS before commit a0ceaf5050faf419401fe1b83acfa950ec8a8a89

## Timeline

- 2016-09-20: disclosed: Initial discovery by Shi Ji
- 2016-10-30: disclosed: Reported as an incomplete fix for CVE-2016-7563
- 2016-11-07: patched: Fix identified in MuJS git repository
- 2017-01-18: advisory: NVD publication date

## References

- [http://www.openwall.com/lists/oss-security/2016/10/30/13](http://www.openwall.com/lists/oss-security/2016/10/30/13)
- [http://www.openwall.com/lists/oss-security/2016/10/30/4](http://www.openwall.com/lists/oss-security/2016/10/30/4)
- [http://www.openwall.com/lists/oss-security/2016/11/07/5](http://www.openwall.com/lists/oss-security/2016/11/07/5)
- [http://www.securityfocus.com/bid/94150](http://www.securityfocus.com/bid/94150)
- [https://bugs.ghostscript.com/show_bug.cgi?id=697136](https://bugs.ghostscript.com/show_bug.cgi?id=697136)

## Related threats

- [MuJS numeric conversion overflow in jsR_isindex](https://junglewise.ai/threats/cve-2026-88362-mujs-e892c9fdb-contains-an-incorrect-numeric-conversion)
- [Artifex Software MuJS integer overflow in MakeDay function](https://junglewise.ai/threats/cve-2017-5628-artifex-software-mujs-integer-overflow-in-makeday-function)
- [Artifex Software MuJS integer overflow in js_pushstring](https://junglewise.ai/threats/cve-2017-5627-artifex-software-mujs-integer-overflow-in-js-pushstring)
- [Artifex Software MuJS heap overflow in Fp_toString](https://junglewise.ai/threats/cve-2016-7564-artifex-software-mujs-heap-overflow-in-fp-tostring)
- [Artifex Software MuJS out-of-bounds read in chartorune](https://junglewise.ai/threats/cve-2016-7563-artifex-software-mujs-out-of-bounds-read-in-chartorune)