# CVE-2026-89494

## Summary

- **CVE ID:** CVE-2026-89494
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/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:

ocfs2: validate lengths in dlm_mig_lockres_handler

A node receiving a DLM_MIG_LOCKRES message trusts several fields of the
peer-supplied dlm_migratable_lockres without validation.  num_locks and
lockname_len are bounded only on the sending side, and the message is
never checked to actually carry num_locks migratable_lock entries.  As a
result dlm_process_recovery_data() walks mres->ml[0..num_locks) past the
kmalloc(data_len) copy of the message (an out-of-bounds read that ends in
a BUG_ON panic), and dlm_init_lockres() copies lockname_len bytes into the
fixed 32-byte o2dlm_lockname slab object (a heap out-of-bounds write). 
Both are reachable by any node in the domain.

Validate these fields right after dlm_grab(), before anything uses them --
including the not-joined error path, which already prints mres->lockname
with the unbounded lockname_len as a %.*s precision.  Reject the message
unless lockname_len <= DLM_LOCKID_NAME_MAX, num_locks <=
DLM_MAX_MIGRATABLE_LOCKS (the bound the sender already asserts), and the
payload is large enough to hold the claimed locks.  Conforming recovery
and migration messages are unaffected.

## Affected Products

- Linux — Linux (6714d8e86bf443f6f7af50f9d432025649f091f5)
- Linux — Linux (2.6.16)
- 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/f33041906885f96e190cde54e61ddc69de39e3ee)
- [CNA](https://git.kernel.org/stable/c/50c4cc9183e11f83427efbf770f54851f4471c02)
- [CNA](https://git.kernel.org/stable/c/a8facb1670b4a0612183198e758d9539ef628ed9)
- [CNA](https://git.kernel.org/stable/c/b54e03d9b3697d25f4a0063cf717d459c5e3ad94)
- [CNA](https://git.kernel.org/stable/c/4a5798253212093b9ff7d90c6cfbe348bcda1594)
- [CNA](https://git.kernel.org/stable/c/dce05b17db862f47ff60614017abe639b2e71cad)
- [CNA](https://git.kernel.org/stable/c/0e999d56917f861f97adb961617b1828c9eb4733)
- [CNA](https://git.kernel.org/stable/c/77686fa5bba135252d348e2dacf481fc19f60c41)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.70%
- **EPSS Percentile:** 51.6

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