CVE-2025-68821

System hang via missing FUSE inode reference

Published Jan 13, 2026 · Updated Jan 13, 2026

Deadlock in Linux Kernel 6.9 and affected stable branches allows local users to hang the system through FUSE readahead reclaim. fuse_prepare_release() skips taking an inode reference when the FUSE server lacks open support, allowing reclaim to evict that inode while its readahead folio remains locked. Exploitation requires low-privileged local access, an active FUSE server without open support, an in-flight readahead request, and server-triggered reclaim; the resulting circular wait leaves kernel work blocked indefinitely.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in Linux Kernel 6.9 and affected stable branches allows local users to hang the system through FUSE readahead reclaim. fuse_prepare_release() skips taking an inode reference when the FUSE server lacks open support, allowing reclaim to evict that inode while its readahead folio remains locked. Exploitation requires low-privileged local access, an active FUSE server without open support, an in-flight readahead request, and server-triggered reclaim; the resulting circular wait leaves kernel work blocked indefinitely.

The record

CVE
CVE-2025-68821
Published
Jan 13, 2026
Updated
Jan 13, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 13, 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=6.9
  2. Affected versionversion=7d38aa079ed859b73f4460aab89c7619b04963b8 <4703bc0e8cd3409acb1476a70cb5b7ff943cf39a
  3. Affected versionversion=a39f70d63f4373a598820d9491719e44cd60afe9
  4. Affected versionversion=c7ec75f3cbf73bd46f479f7d6942585f765715da <cf74785c00b8b1c0c4a9dd74bfa9c22d62e2d99f
  5. Affected versionversion=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <bd5603eaae0aabf527bfb3ce1bb07e979ce5bd50
  6. Affected versionversion=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <e0d6de83a4cc22bbac72713f3a58121af36cc411
  7. Affected versionversion=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <fbba8b00bbe4e4f958a2b0654cc1219a7e6597f6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.9; version=7d38aa079ed859b73f4460aab89c7619b04963b8 <4703bc0e8cd3409acb1476a70cb5b7ff943cf39a; version=a39f70d63f4373a598820d9491719e44cd60afe9; version=c7ec75f3cbf73bd46f479f7d6942585f765715da <cf74785c00b8b1c0c4a9dd74bfa9c22d62e2d99f; version=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <bd5603eaae0aabf527bfb3ce1bb07e979ce5bd50; version=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <e0d6de83a4cc22bbac72713f3a58121af36cc411; version=e26ee4efbc79610b20e7abe9d96c87f33dacc1ff <fbba8b00bbe4e4f958a2b0654cc1219a7e6597f6

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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

T1499Endpoint Denial of Service

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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