CVE-2026-89656

Kernel memory corruption via mismatched CRUSH bucket ID

Published Sep 11, 2026 · Updated Sep 11, 2026

Out-of-bounds write in Linux kernel libceph allows attackers to corrupt kernel memory through a malformed CRUSH map. The crush_decode() function stores bucket data by array slot but accepts an encoded ID that makes bucket_perm_choose() expand a larger permutation into another bucket's smaller workspace. Reachability requires processing a noncanonical CRUSH bucket ID; public upstream material does not identify the attacker's required access or a consequence beyond the demonstrated four-byte out-of-bounds write.

CVSS severityUnavailable
Unscored
EPSS probability0.52%
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 Linux kernel libceph allows attackers to corrupt kernel memory through a malformed CRUSH map. The crush_decode() function stores bucket data by array slot but accepts an encoded ID that makes bucket_perm_choose() expand a larger permutation into another bucket's smaller workspace. Reachability requires processing a noncanonical CRUSH bucket ID; public upstream material does not identify the attacker's required access or a consequence beyond the demonstrated four-byte out-of-bounds write.

The record

CVE
CVE-2026-89656
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
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=4.11
  2. Affected versionversion=66a0e2d579dbec5c676cfe446234ffebb267c564 <00562ccd4e88d092b9b851df50fad20442bfeb24
  3. Affected versionversion=66a0e2d579dbec5c676cfe446234ffebb267c564 <3516a4131c4e45d62ee4e42e82c36930e8c1fbbd
  4. Affected versionversion=66a0e2d579dbec5c676cfe446234ffebb267c564 <3cde4a8302301679937474a5f7a851394cc1bd11
  5. Affected versionversion=66a0e2d579dbec5c676cfe446234ffebb267c564 <79900d978158b2d80eef952fc41b9e4dc58d7b83

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=4.11; version=66a0e2d579dbec5c676cfe446234ffebb267c564 <00562ccd4e88d092b9b851df50fad20442bfeb24; version=66a0e2d579dbec5c676cfe446234ffebb267c564 <3516a4131c4e45d62ee4e42e82c36930e8c1fbbd; version=66a0e2d579dbec5c676cfe446234ffebb267c564 <3cde4a8302301679937474a5f7a851394cc1bd11; version=66a0e2d579dbec5c676cfe446234ffebb267c564 <79900d978158b2d80eef952fc41b9e4dc58d7b83

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
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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