CVE-2026-2967 Cesanta Mongoose TCP Sequence Number net_builtin.c getpeer verification of source
An attacker can bypass source verification in Cesanta Mongoose's TCP sequence number handler, potentially spoofing communication channels.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-2967?
CVE-2026-2967 is a medium-severity vulnerability in Cesanta Mongoose, published on 23 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This affects the function getpeer of the file /src/net_builtin.c of the component TCP Sequence Number Handler. The manipulation leads to improper verification of source of a communication channel. The attack may be initiated remotely. The attack's complexity is rated as high. The exploitability is reported as difficult. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
Weakness: CWE-940
Which versions are affected by CVE-2026-2967?
It affects 1 product.
Products include Cesanta Mongoose.
How do I fix CVE-2026-2967?
No fix published yet.
Is CVE-2026-2967 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-2967 exists.
Other vulnerabilities in Cesanta Mongoose
Sources
Also known as DEBIAN-CVE-2026-2967, GHSA-c6h3-vh8h-r8mj, JLSEC-2026-367, UBUNTU-CVE-2026-2967.