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CVE-2026-49429

Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl

HIGH
7.8
CVSS Score
Published: August 19, 2026 at 05:15 AM UTC
Updated: September 1, 2026 at 08:21 PM UTC
1 product affected across 1 vendorFreeBSD

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Severity
HIGH7.8
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

The ZFS_IOC_USERSPACE_MANY ioctl, used by zfs-userspace(8), truncated a 64-bit output buffer size to a 32-bit integer for the kernel allocation, but used the original 64-bit size as the buffer limit when writing records. A local user with the "userused" delegated ZFS permission can trigger a kernel heap overflow via the ZFS_IOC_USERSPACE_MANY ioctl, potentially escalating privileges.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

FreeBSD· Freebsd
95%
14.3-RELEASE ≤ v < p1614.4-RELEASE ≤ v < p715.0-RELEASE ≤ v < p1115.1-RELEASE ≤ v < p114.314.3 p114.3 p1014.3 p1114.3 p1214.3 p1314.3 p1414.3 p1514.3 p214.3 p314.3 p414.3 p514.3 p614.3 p714.3 p814.3 p914.3-RELEASE14.414.4 p114.4 p214.4 p314.4 p414.4 p514.4 p614.4 rc114.4-RELEASE15.015.0 p115.0 p1015.0 p215.0 p315.0 p415.0 p515.0 p615.0 p715.0 p815.0 p915.0-RELEASE15.115.1 rc215.1 rc3-p115.1-RELEASE
Affected range stops below p1, so it looks safe — our inference, not a vendor statement
Affected range stops below p11, so it looks safe — our inference, not a vendor statement
Affected range stops below p16, so it looks safe — our inference, not a vendor statement
Affected range stops below p7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisory
Source: cverecord
https://security.freebsd.org/advisories/FreeBSD-SA-26:40.zfs.asc

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHCISA-ADP
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-122

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