CVE-2026-5245 Cesanta Mongoose mDNS Record mongoose.c handle_mdns_record stack-based overflow

Medium 6.3 Published 2 Apr 2026 Updated 2 Apr 2026

Remote attackers can trigger a stack-based buffer overflow in the mDNS handler, potentially leading to code execution or denial of service.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-5245?

CVE-2026-5245 is a medium-severity memory corruption vulnerability in Cesanta Mongoose, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability was found in Cesanta Mongoose up to 7.20. This impacts the function handle_mdns_record of the file mongoose.c of the component mDNS Record Handler. Performing a manipulation of the argument buf results in stack-based buffer overflow. Remote exploitation of the attack is possible. A high degree of complexity is needed for the attack. The exploitability is said to be difficult. The exploit has been made public and could be used. Upgrading to version 7.21 will fix this issue. The patch is named 0d882f1b43ff2308b7486a56a9d60cd6dba8a3f1. You should upgrade the affected component. The vendor was contacted early, responded in a very professional manner and quickly released a fixed version of the affected product.

Weakness: CWE-121, CWE-119

Which versions are affected by CVE-2026-5245?

It affects 1 product.

Products include Cesanta Mongoose.

How do I fix CVE-2026-5245?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-5245 being exploited?

There is no known exploitation of CVE-2026-5245 in the wild and no public exploit code.

All Cesanta Mongoose vulnerabilities

Sources

Also known as DEBIAN-CVE-2026-5245, GHSA-2rqj-7x75-2684, JLSEC-2026-370, UBUNTU-CVE-2026-5245.