CVE-2026-49427

posixshm: largepage shared memory objects not explicitly wired

State: Published
Severity: 8.8 High
Published: Aug 19, 2026
Updated: Aug 20, 2026
Reserved: May 29, 2026

Description

Pages belonging to largepage shared memory objects were not explicitly wired. When sendfile(2) transmitted such an object with the SF_NOCACHE flag, it freed the underlying pages after transmission even though existing mappings still referred to them.

An unprivileged local user can abuse the bug to access freed kernel memory. This can be exploited to escalate privileges.

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-826 Premature Release of Resource During Expected Lifetime

Affected Products

Product	Versions
FreeBSDFreeBSD	15.1-RELEASE to before p1Affected 15.0-RELEASE to before p11Affected 14.4-RELEASE to before p7Affected 14.3-RELEASE to before p16Affected

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:44.posixshm.ascvendor-advisory

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