CVE-2026-15449

TOCTOU double copyin in illumos dld ioctl handling causes kernel heap corruption

Published Jul 16, 2026 CVSS 4.0 · 5.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

Vendor Solution

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


Vendor Workaround

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

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Illumos
Illumos illumos-gate
Omnios
Omnios omnios
Tritondatacenter
Tritondatacenter smartos
Vendors & Products Illumos
Illumos illumos-gate
Omnios
Omnios omnios
Tritondatacenter
Tritondatacenter smartos
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
illumos
Published
Updated
Jul 17, 2026, 12:42 PM
Reserved
Jul 10, 2026, 7:23 PM
Status
Deferred
Published
Jul 16, 2026, 8:16 PM
Modified
Jul 17, 2026, 6:45 PM