A time-of-check to time-of-use (TOCTOU) flaw in the illumos data-link pseudo-driver (dld) affects handling of the DLDIOC_GETMACPROP and DLDIOC_SETMACPROP ioctls on /dev/dld. drv_ioc_prop_common() in usr/src/uts/common/io/dld/dld_drv.c copies the dld_ioc_macprop_t ioctl header in once to read its pr_valsize field, sizes and allocates a kernel heap buffer from that value, and then copies the full request in a second time from the same unprivileged user address. A concurrent thread can enlarge pr_valsize between the two copyins, so the second copyin and the subsequent property handling write beyond the end of the undersized allocation and corrupt the kernel heap. An unprivileged local user, including one confined to a non-global zone that owns a datalink, can trigger this to panic the system. The resulting kernel heap corruption may be usable for further compromise.

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

Update your illumos distribution to one that includes the fix for issue 18020.


Workaround

No mitigation is available. The referenced notification includes a DTrace script that detects exploitation attempts.

History

Thu, 16 Jul 2026 19:45:00 +0000

Type Values Removed Values Added
Description A time-of-check to time-of-use (TOCTOU) flaw in the illumos data-link pseudo-driver (dld) affects handling of the DLDIOC_GETMACPROP and DLDIOC_SETMACPROP ioctls on /dev/dld. drv_ioc_prop_common() in usr/src/uts/common/io/dld/dld_drv.c copies the dld_ioc_macprop_t ioctl header in once to read its pr_valsize field, sizes and allocates a kernel heap buffer from that value, and then copies the full request in a second time from the same unprivileged user address. A concurrent thread can enlarge pr_valsize between the two copyins, so the second copyin and the subsequent property handling write beyond the end of the undersized allocation and corrupt the kernel heap. An unprivileged local user, including one confined to a non-global zone that owns a datalink, can trigger this to panic the system. The resulting kernel heap corruption may be usable for further compromise.
Title TOCTOU double copyin in illumos dld ioctl handling causes kernel heap corruption
Weaknesses CWE-122
CWE-367
References
Metrics cvssV4_0

{'score': 5.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: illumos

Published:

Updated: 2026-07-16T19:27:16.036Z

Reserved: 2026-07-10T19:23:40.195Z

Link: CVE-2026-15449

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses