Vulnerability · Published Aug 26, 2026 · Assigned by freebsd

CVE-2026-58094TOCTOU race in POSIX shared memory large page configuration

High 7.8

In plain English

A high-severity security flaw in FreeBSD from FreeBSD. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 3.1)7.8High

Exploit odds (30 days)0.1%top 98.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

The FIOSSHMLPGCNF ioctl(2) operation configures the page size for a largepage shared memory object. This is intended to be used immediately after creating the object, before any memory is allocated for the object. The handler checked whether a page size had already been configured without holding the rangelock. Two concurrent callers could both observe an unconfigured object and set conflicting page sizes, leaving the object in an inconsistent state. An unprivileged local user can exploit this race to escalate privileges.

Affected products (as reported)

Vendor	Product	Versions
FreeBSD	FreeBSD	15.1-RELEASE – before p315.0-RELEASE – before p1314.4-RELEASE – before p9

Weakness: CWE-367 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:63.posixshm.asc vendor-advisory