CVE-2026-86716 Cesanta mJS mjs_tok.c skip_spaces_and_comments heap-based overflow
A heap-based buffer overflow in the Cesanta mJS JavaScript engine allows remote attackers to execute arbitrary code or cause denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-86716?
CVE-2026-86716 is a medium-severity memory corruption vulnerability in Cesanta mJS, published on 8 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-86716?
How do I fix CVE-2026-86716?
No fix has been published for CVE-2026-86716 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-86716 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86716 exists.
Sources
Also known as GHSA-mcxw-v86m-vj8g.