CVE-2026-15449: TOCTOU double copyin in illumos dld ioctl handling causes kernel heap corruption

Severity: medium (CVSS 5.8 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-16 · updated 2026-07-17
Weakness: CWE-122

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.

Affected products

illumos-gate: all versions
OmniOS: from any before r151054; from r151058 before r151058j; from r151056 before r151056aj; from r151054 before r151054bj — fixed in r151054, r151054bj, r151056aj, r151058j
Triton Data Center SmartOS: from any before 202060709 — fixed in 202060709

How to fix

Upgrade to a fixed version: OmniOS r151054, r151054bj, r151056aj, r151058j; Triton Data Center SmartOS 202060709. Check the vendor advisory for mitigations.

References

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