CVE-2026-89653Network attack vector

Kernel stack corruption via unchecked MDS rank

Published Sep 11, 2026 · Updated Sep 11, 2026

Out-of-bounds write in the Linux CephFS client allows attackers controlling a Ceph monitor to corrupt kernel stack memory via an MDS map. During MDS-map decoding, fs/ceph/mdsmap.c accepts an export_targets rank at or above CEPH_MAX_MDS, and check_new_map() passes it to set_bit() as an index into a fixed stack bitmap. Exposure requires an active CephFS kernel client to accept the crafted map from a controlling monitor; the published fix does not establish a crash or code-execution outcome.

CVSS severityUnavailable
Unscored
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in the Linux CephFS client allows attackers controlling a Ceph monitor to corrupt kernel stack memory via an MDS map. During MDS-map decoding, fs/ceph/mdsmap.c accepts an export_targets rank at or above CEPH_MAX_MDS, and check_new_map() passes it to set_bit() as an index into a fixed stack bitmap. Exposure requires an active CephFS kernel client to accept the crafted map from a controlling monitor; the published fix does not establish a crash or code-execution outcome.

The record

CVE
CVE-2026-89653
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.15
  2. Affected versionversion=d517b3983dd3106ca92d6c5d0d09415a4a09481c <4d298880f82c42383b36946bafde7ccf4d804c9b
  3. Affected versionversion=d517b3983dd3106ca92d6c5d0d09415a4a09481c <736adee11af36e407ed902264f8b2fb5cf94b62f
  4. Affected versionversion=d517b3983dd3106ca92d6c5d0d09415a4a09481c <96c3f5fbb0d5386e7111426f047f98cec4586674
  5. Affected versionversion=d517b3983dd3106ca92d6c5d0d09415a4a09481c <aedc9053d909508a5f56c3f49f885fc030df4730

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=d517b3983dd3106ca92d6c5d0d09415a4a09481c <4d298880f82c42383b36946bafde7ccf4d804c9b; version=d517b3983dd3106ca92d6c5d0d09415a4a09481c <736adee11af36e407ed902264f8b2fb5cf94b62f; version=d517b3983dd3106ca92d6c5d0d09415a4a09481c <96c3f5fbb0d5386e7111426f047f98cec4586674; version=d517b3983dd3106ca92d6c5d0d09415a4a09481c <aedc9053d909508a5f56c3f49f885fc030df4730

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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