CVE-2026-91018 Double Free in lwIP (lightweight IP)
A double free vulnerability in the lwIP library allows attackers to cause denial of service or execute arbitrary code on affected systems.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-91018?
CVE-2026-91018 is a high-severity use after free vulnerability in lwIP API, published on 22 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
lwIP (Lightweight IP) has a double free vulnerability, which could crash the system, cause a DoS, memory corruption, or allow code execution on the victim system.
Weakness: CWE-415
Which versions are affected by CVE-2026-91018?
How do I fix CVE-2026-91018?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-91018 being exploited?
There is no known exploitation of CVE-2026-91018 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-91018, GHSA-rmx4-24pf-8x6h, UBUNTU-CVE-2026-91018.