---
title: "CVE-2026-88390: Espruino - Out of Bounds Write"
description: "Espruino 2v29 contains a buffer overflow caused by an out-of-bounds write in jslGetTokenValueAsString() when processing overlong JavaScript tokens, letting attackers cause memory corruption and denial of service, exploit requires crafted JavaScript input."
url: https://panop.io/threat-heartbeat/CVE-2026-88390/
---

# CVE-2026-88390 Espruino - Out of Bounds Write

Espruino 2v29 contains a buffer overflow caused by an out-of-bounds write in jslGetTokenValueAsString() when processing overlong JavaScript tokens, letting attackers cause memory corruption and denial of service, exploit requires crafted JavaScript input.

CVSS base score 7.7 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.17% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-88390)

## Details

Type

Out of Bounds Write

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

Published

24 September 2026

Updated

15 October 2026

Weakness

[CWE-787](https://cwe.mitre.org/data/definitions/787.html)

## Vendor fix

Update to the latest version of Espruino.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-88390](https://nvd.nist.gov/vuln/detail/CVE-2026-88390)
- [https://github.com/espruino/Espruino/commit/ecd7d43e084ba9aafa8245609347fe0f4383b38c](https://github.com/espruino/Espruino/commit/ecd7d43e084ba9aafa8245609347fe0f4383b38c)
- [https://github.com/espruino/Espruino/issues/2744](https://github.com/espruino/Espruino/issues/2744)

[← All CVEs](https://panop.io/threat-heartbeat/)

## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

[Book a demo](https://panop.io/demo)