---
id: CVE-2026-88390
title: >-
  An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino
  2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong
  token to trigger a one-byte write beyond the JsLex.token buffer in
  RELEASE/NO_ASS…
summary: >-
  An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino
  2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong
  token to trigger a one-byte write beyond the JsLex.token buffer in
  RELEASE/NO_ASS…
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'
cwe:
  - CWE-787
published: '2026-09-24'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:08:55.030'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-88390'
references:
  - url: >-
      https://github.com/espruino/Espruino/commit/ecd7d43e084ba9aafa8245609347fe0f4383b38c
    label: cve@mitre.org
  - url: 'https://github.com/espruino/Espruino/issues/2744'
    label: cve@mitre.org
  - url: 'https://github.com/espruino/Espruino/issues/2744'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-24T18:59:21.695501Z'
ingestedAt: '2026-09-24T16:47:15.848Z'
epss: 0.00173
epssPercentile: 0.05931
---

## Overview

An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino 2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong token to trigger a one-byte write beyond the JsLex.token buffer in RELEASE/NO_ASSERT builds. The out-of-bounds write corrupts the adjacent tokenValue pointer, resulting in memory corruption and potentially causing application crashes or denial of service.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.