CVE-2026-89494: Linux Vulnerability (CVSS 9.8)

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.63%

48.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 6714d8e86bf443f6f7af50f9d432025649f091f5, < 4a5798253212093b9ff7d90c6cfbe348bcda1594; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < dce05b17db862f47ff60614017abe639b2e71cad; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < 0e999d56917f861f97adb961617b1828c9eb4733; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < 77686fa5bba135252d348e2dacf481fc19f60c41; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < f33041906885f96e190cde54e61ddc69de39e3ee; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < 50c4cc9183e11f83427efbf770f54851f4471c02; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < a8facb1670b4a0612183198e758d9539ef628ed9; >= 6714d8e86bf443f6f7af50f9d432025649f091f5, < b54e03d9b3697d25f4a0063cf717d459c5e3ad94
Linux	Linux	2.6.16

References

Timeline

Published: Sep 11, 2026
Last Modified: Sep 14, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89494?

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.

How severe is CVE-2026-89494?

CVE-2026-89494 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.63% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89494?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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