---
id: CVE-2026-89507
title: 'kernel: RDMA/ucma: Lock the handler in ucma_write_cm_event() (CVE-2026-89507)'
summary: >-
  A flaw was found in the Linux kernel's RDMA/ucma component. A race condition
  exists in the `ucma_write_cm_event()` function where it re-reads a critical
  file pointer multiple times without proper locking. This allows another
  function, `ucm…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe: CWE-367
vendor: Red Hat
product: Red Hat OpenShift Container Platform 4
affected:
  - openshift_container_platform 4
published: '2026-09-11'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T10:28:26+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89507.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89507.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89507'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532319'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89507'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89507'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89507.mbox
  - url: 'https://git.kernel.org/stable/c/0be1955040a2eceed0ecfc387fdc92305411d273'
  - url: 'https://git.kernel.org/stable/c/4f8bb11dd2ff365e7cff1c9964ab4607292d364e'
  - url: 'https://git.kernel.org/stable/c/f4cc21c6a8e9d392871477f9fd98d68e5ad80272'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00127
epssPercentile: 0.02711
scores:
  vendor: 4.7
  cna: 7.8
ingestedAt: '2026-09-14T15:23:07.475Z'
---

## Overview

A flaw was found in the Linux kernel's RDMA/ucma component. A race condition exists in the `ucma_write_cm_event()` function where it re-reads a critical file pointer multiple times without proper locking. This allows another function, `ucma_migrate_id()`, to change the file pointer mid-operation. An unprivileged local user can exploit this to cause list corruption, trigger a kernel crash, and leave a mutex locked indefinitely, resulting in a denial of service.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89507.json)

**kernel: RDMA/ucma: Lock the handler in ucma_write_cm_event()** — rated Moderate by Red Hat. Released 2026-09-11, updated 2026-09-16.

Affected:

- Red Hat OpenShift Container Platform 4

No fix planned:

- Red Hat OpenShift Container Platform 4

Not affected:

- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4

## Remediation

Affected