CVE-2026-86716: Cesanta mJS mjs_tok.c skip_spaces_and_comments heap-based overflow

Severity: high (CVSS 7.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-08 · updated 2026-09-08
Weakness: CWE-119

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.

Affected products

Cesanta mJS: 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 (+21)

References

https://github.com/cesanta/mjs/
https://github.com/cesanta/mjs/issues/324
https://vuldb.com/cve/CVE-2026-86716
https://vuldb.com/submit/910881
https://vuldb.com/submit/910882
https://vuldb.com/vuln/399773
https://vuldb.com/vuln/399773/cti

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