External risk intelligence

Linux Kernel OCFS2 Directory Entry Count Validation Flaw.

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-89492

This vulnerability exists within the OCFS2 file system driver in the Linux kernel. It requires mounting a crafted file system image or interacting with an already mounted file system. It is a local, kernel-level issue related to metadata parsing and is not exposed as a public-facing network service or internet-reachable interface.

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability has been identified in the Linux kernel's OCFS2 file system that could allow for out-of-bounds reads when processing directory metadata. This issue, discovered by automated security tooling, involves the way directory index entry counts are validated, potentially leading to data corruption or system instability if a crafted on-disk image is mounted.

Unchecked directory counts may allow unauthorized data reads.
This affects file system integrity and system stability.
Confirm if OCFS2 file systems are in use and exposed to untrusted images.

Attack Path

How an attacker could exploit the issue

An attacker could potentially compromise a Linux system by creating a specially crafted file system image. When this malicious image is mounted, operations like looking up a file's path or checking its status could trigger the vulnerability by causing the system to read beyond the intended memory boundaries. This could lead to a system crash or other security compromises.

Requires mounting a crafted file system.
Triggered by file system operations like `stat()` or `open()`.
Potential for memory corruption and system instability.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to read arbitrary kernel memory when processing metadata for an OCFS2 file system. This occurs when directory indexing information is read from disk and the counts are not properly validated against the block's capacity, leading to an out-of-bounds read.

Kernel memory.
Reading crafted file system metadata.
Information disclosure.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability impacts the Linux kernel's OCFS2 file system, specifically how it reads directory metadata. System owners and infrastructure teams are likely responsible for managing file systems. The first practical step is to identify all systems using OCFS2, determine if they are business-critical or exposed, locate the accountable owner, and then plan remediation, which may involve vendor coordination or carefully planned maintenance.

Identify OCFS2 usage and owners.
Verify OCFS2 metadata integrity.
Plan file system remediation or vendor engagement.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is the OCFS2 component in the Linux kernel?

OCFS2, or Oracle Cluster File System 2, is a shared-disk file system for Linux. It allows multiple servers to concurrently access the same storage device, which is commonly used in enterprise environments to support clustered applications and databases that require shared data access.

How does CVE-2026-89492 trigger an out-of-bounds read?

This vulnerability is an improper input validation flaw. When the OCFS2 driver processes directory index metadata, it fails to verify that the entry count matches the block's physical capacity. If a crafted image provides an artificially high count, the kernel reads memory beyond the intended block boundaries during standard lookups.

What is required to trigger this vulnerability?

The vulnerability requires mounting a specially crafted OCFS2 file system image. Once the malicious image is mounted, common operations like calling stat() or open() on a directory are enough to trigger the flawed memory access. Simply interacting with a standard, untrusted file or network socket will not trigger this issue.

Is this CVE reachable via the internet?

According to Halo Surface Signal, this vulnerability is very unlikely to be exposed to the internet. It is a local, kernel-level issue occurring during file system metadata processing. Because it requires mounting a specific file system image, it is not accessible as a public-facing network service.

How should I respond to this threat?

Start by auditing your infrastructure to identify which systems currently mount OCFS2 file systems. Once you have a list, verify if these systems handle storage or disk images from untrusted sources. Finally, coordinate with your Linux distribution provider or kernel maintainers to apply the necessary patches that enforce metadata boundary checks.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.