CVE-2026-89644

Resource exhaustion via leaked extent map references

Published Sep 11, 2026 · Updated Sep 11, 2026

Resource leakage in the Linux kernel allows local users to consume kernel memory through failed NOCOW direct I/O writes. In btrfs_dio_iomap_begin(), an error from btrfs_create_dio_extent() returns without releasing the extent map obtained by btrfs_get_extent(). Reachability requires a writable NOCOW range on Btrfs and an ordered-extent allocation failure; repeated failures can degrade availability, with no reported data disclosure or modification.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource leakage in the Linux kernel allows local users to consume kernel memory through failed NOCOW direct I/O writes. In btrfs_dio_iomap_begin(), an error from btrfs_create_dio_extent() returns without releasing the extent map obtained by btrfs_get_extent(). Reachability requires a writable NOCOW range on Btrfs and an ordered-extent allocation failure; repeated failures can degrade availability, with no reported data disclosure or modification.

The record

CVE
CVE-2026-89644
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

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=4.7
  2. Affected versionversion=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d
  3. Affected versionversion=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <3f950867c307c5413d628a153ac44915bd117ffd
  4. Affected versionversion=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.7; version=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d; version=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <3f950867c307c5413d628a153ac44915bd117ffd; version=5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af <f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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