CVE-2026-88390
Received Received - Intake

Out-of-Bounds Write in Espruino JavaScript Engine

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: MITRE

Description
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.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-88390
EUVD
EUVD-2026-86313

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
espruino espruino 2.29

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.

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Executive Summary

This vulnerability is an out-of-bounds write flaw in the jslGetTokenValueAsString() function of Espruino 2v29. Crafted JavaScript input with an overlong token causes a one-byte write past the JsLex.token buffer. This corrupts the adjacent tokenValue pointer, leading to memory corruption that may crash the application or cause denial of service.

Detection Guidance

This vulnerability is specific to Espruino JavaScript engine versions and requires crafted JavaScript input to trigger. Detection involves checking for crashes or memory corruption when processing JavaScript tokens. No direct network detection commands exist; focus on application logs and crashes during JavaScript parsing.

Impact Analysis

The vulnerability could allow attackers to crash the Espruino application or cause denial of service by providing specially crafted JavaScript input. In worst cases, it might enable further exploitation if combined with other vulnerabilities, though no direct code execution is mentioned.

Mitigation Strategies

Update Espruino to a patched version if available. Avoid processing untrusted JavaScript input. Monitor application crashes or memory corruption events. Consider disabling JavaScript parsing if not required for functionality.

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