CVE-2026-86716
Deferred Deferred - Pending Action

Heap-based Buffer Overflow in Cesanta mJS

Vulnerability report for CVE-2026-86716, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-08

Last updated on: 2026-09-08

Assigner: VulDB

Description

A vulnerability was determined in Cesanta mJS up to 1.26. Affected is the function skip_spaces_and_comments of the file src/mjs_tok.c. Executing a manipulation can lead to heap-based buffer overflow. The attack can be launched remotely. The exploit has been publicly disclosed and may be utilized. The project was informed of the problem early through an issue report but has not responded yet.

CVSS Scores

EPSS Scores

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Meta Information

Published
2026-09-08
Last Modified
2026-09-08
Generated
2026-09-29
AI Q&A
2026-09-09
EPSS Evaluated
2026-09-27
NVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
cesanta mjs to 1.26 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-122 A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
CWE-119 The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Attack-Flow Graph

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Executive Summary

This vulnerability is a heap-based buffer overflow in Cesanta mJS up to version 1.26, specifically in the function skip_spaces_and_comments within the file src/mjs_tok.c. It allows remote attackers to execute arbitrary code or cause a denial of service by manipulating input data.

Impact Analysis

The vulnerability can lead to remote code execution or system crashes. Attackers could exploit it to gain unauthorized access, steal data, or disrupt services if the affected software is used in a network-facing application.

Mitigation Strategies

Update Cesanta mJS to the latest version beyond 1.26 to address the heap-based buffer overflow in the skip_spaces_and_comments function. If an update is not available, consider disabling or restricting access to affected systems until a patch is released.

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