# CVE-2026-89489

## Summary

- **CVE ID:** CVE-2026-89489
- **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:

openrisc: fix arbitrary kernel memory access via or1k_atomic syscall

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]

## Affected Products

- Linux — Linux (9d02a4283e9ce4e9ca11ff00615bdacdb0515a1a)
- Linux — Linux (3.1)
- 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 (5.10.270)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/a520e8cac54fb403f3800125b606f55fcad42cb9)
- [CNA](https://git.kernel.org/stable/c/d64a75369cd0f2ee79afcc9d9ca34a3890989379)
- [CNA](https://git.kernel.org/stable/c/b53435c079c78f89f70a62dd5a322cca4e292b34)
- [CNA](https://git.kernel.org/stable/c/78004e9a87f240df03e2f73120d291763c32e0a7)
- [CNA](https://git.kernel.org/stable/c/bf310718c6fa6adeee06d207a55489546d860e2c)
- [CNA](https://git.kernel.org/stable/c/497cba0b02e5555d99fe9ee1dc478af743ab7f7a)
- [CNA](https://git.kernel.org/stable/c/1f2e92e499d863f81df1732af59b4a3559969193)
- [CNA](https://git.kernel.org/stable/c/574ae2ac2b314aa33498cd2c28add106cbe644f2)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.14%
- **EPSS Percentile:** 3.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-19._