CVE-2026-39457: freebsd Stack-based Buffer Overflow

Vulnerability summary

CVE-2026-39457 is a high (CVSS 7.8) Stack-based Buffer Overflow vulnerability in freebsd. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.9% of scored vulnerabilities.

Timeline

1. 30-04-2026
   PublishedVulnerability first disclosed.
2. 01-05-2026
   Last modifiedVulnerability information updated.

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.

• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).