High severity · published Aug 19, 2026
CVE-2026-49428
posixshm: system calls can incorrectly free memory of largepage objects
8.4
CVSS
0.3%
EPSS
No
On KEV
Description
Certain system calls, such open(2) with the O_TRUNC flag set, and fspacectl(2), could incorrectly free memory in largepage objects. These operations are not permitted on largepage objects, but the implementation did not verify this.
An unprivileged local user can abuse the bug to access freed kernel memory. This can be exploited to escalate privileges.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
FreeBSD · FreeBSD
15.1-RELEASE before p1; 15.0-RELEASE before p11; 14.4-RELEASE before p7; 14.3-RELEASE before p16 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49428
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49428
Vendor Advisory
https://security.freebsd.org/advisories/FreeBSD-SA-26:44.posixshm.asc
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