CVE-2026-86716 Details
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.
A heap-based buffer overflow vulnerability has been identified in Cesanta mJS versions through 1.26. The issue arises in the lexer function 'skip_spaces_and_comments' within 'src/mjs_tok.c'. When 'mjs_exec()' is called with a string that ends in whitespace, such as a newline, the function reads beyond the null-terminated input buffer. This vulnerability can be exploited remotely, leading to a crash, particularly when the input is a single newline byte.
Users are advised to update to the latest version of Cesanta mJS, as this vulnerability has been addressed in the most recent release.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 8, 2026CISA-ADP
Assessed Sep 8, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/cesanta/mjs/ | [email protected] | ProductSource CodeVendor |
| https://github.com/cesanta/mjs/issues/324 | [email protected] | ExploitIssue TrackingTechnical AnalysisVendor |
| https://vuldb.com/cve/CVE-2026-86716 | [email protected] | AdvisoryPermission Required |
| https://vuldb.com/submit/910881 | [email protected] | Issue TrackingPermission Required |
| https://vuldb.com/submit/910882 | [email protected] | Issue TrackingPermission Required |
| https://vuldb.com/vuln/399773 | [email protected] | Content Wall |
| https://vuldb.com/vuln/399773/cti | [email protected] | Content Wall |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-119 | Improper Restriction of Operations within the Bounds of a Memory Buffer | [email protected] |
| CWE-122 | Heap-based Buffer Overflow | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Cesanta mJS | <= 1.26 |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 8, 2026 | CVE Modified | CISA-ADP |
| Sep 8, 2026 | New CVE Received | [email protected] |