CVE-2026-39457 Stack overflow via select() file descriptor set overflow
A stack overflow in libnv allows local attackers to corrupt memory and potentially escalate privileges to root.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-39457?
CVE-2026-39457 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 30 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
When exchanging data over a socket, libnv uses select(2) to wait for data to arrive. However, it does not verify whether the provided socket descriptor fits in select(2)'s file descriptor set size limit of FD_SETSIZE (1024).
An attacker who is able to force a libnv application to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, can trigger stack corruption. If the target application is setuid-root, then this could be used to elevate local privileges.
Weakness: CWE-121
Which versions are affected by CVE-2026-39457?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-39457?
No fix has been published for CVE-2026-39457 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-2026-39457 being exploited?
There is no known exploitation of CVE-2026-39457 in the wild and no public exploit code.
Other vulnerabilities in Freebsd Freebsd
Sources
Also known as GHSA-gfv8-jx4x-32h7.