# CVE-2026-89442

## Summary

- **CVE ID:** CVE-2026-89442
- **Severity:** HIGH
- **CVSS Score:** 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 14, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

platform/x86: ISST: Validate socket ID in clos_assoc ioctl

isst_if_clos_assoc() validates the user-supplied socket_id with
'socket_id > topology_max_packages()', but isst_common.sst_inst[] is
allocated with topology_max_packages() entries, so the valid index range
is [0, topology_max_packages()).  The '>' comparison lets
socket_id == topology_max_packages() pass and index one entry past the
array.

In addition, isst_common.sst_inst[socket_id] is NULL for an in-range
package that has no bound TPMI SST instance, and the pointer is used
without a NULL check.  Both the out-of-bounds entry and the NULL pointer
are then dereferenced by map_partition_power_domain_id() and the
following power_domain_info access.

Reject socket_id >= topology_max_packages() and a NULL sst_inst, matching
the checks already performed by get_instance().

## Affected Products

- Linux — Linux (12a7d2cb811dd8a884dea088a2701fcb8d00136e)
- Linux — Linux (6.4)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/0d90ab5f80e19cddfeb0c9fab47a1f34aa932075)
- [CNA](https://git.kernel.org/stable/c/82e707eff9e3b7ef6d96ecc23ea8876d20c7d6ca)
- [CNA](https://git.kernel.org/stable/c/207b4dc6eb100141b122b2602504a1429a4b6558)
- [CNA](https://git.kernel.org/stable/c/a89f07db0cb95c54dac4a8406c79a04e44a73c3c)
- [CNA](https://git.kernel.org/stable/c/c847ea4851ecfa3462cc711ded2c3c3dd8d08ab8)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.16%
- **EPSS Percentile:** 5.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._