CVE-2025-68358

Filesystem allocation hang via unlocked bitfield write

Published Dec 24, 2025 · Updated Dec 24, 2025

Race condition in the Linux kernel's Btrfs space allocator allows local users to hang filesystem allocations during concurrent reclaim. btrfs_clear_space_info_full() clears the shared full bitfield without its lock, so a non-atomic read-modify-write can restore an adjacent flush bit after the reclaim worker exits. The gate is concurrent block-group deletion and data reclaim; once the invariant is lost, later allocation tickets remain blocked because no worker can be queued.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux kernel's Btrfs space allocator allows local users to hang filesystem allocations during concurrent reclaim. btrfs_clear_space_info_full() clears the shared full bitfield without its lock, so a non-atomic read-modify-write can restore an adjacent flush bit after the reclaim worker exits. The gate is concurrent block-group deletion and data reclaim; once the invariant is lost, later allocation tickets remain blocked because no worker can be queued.

The record

CVE
CVE-2025-68358
Published
Dec 24, 2025
Updated
Dec 24, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 24, 2025Record 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=4.8
  2. Affected versionversion=957780eb2788d8c218d539e19a85653f51a96dc1 <38e818718c5e04961eea0fa8feff3f100ce40408
  3. Affected versionversion=957780eb2788d8c218d539e19a85653f51a96dc1 <6f442808a86eef847ee10afa9e6459494ed85bb3
  4. Affected versionversion=957780eb2788d8c218d539e19a85653f51a96dc1 <742b90eaf394f0018352c0e10dc89763b2dd5267

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.8; version=957780eb2788d8c218d539e19a85653f51a96dc1 <38e818718c5e04961eea0fa8feff3f100ce40408; version=957780eb2788d8c218d539e19a85653f51a96dc1 <6f442808a86eef847ee10afa9e6459494ed85bb3; version=957780eb2788d8c218d539e19a85653f51a96dc1 <742b90eaf394f0018352c0e10dc89763b2dd5267

Published CVSS scores

5.5NVDCVSS: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
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5SUSECVSS: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

T1499.004Endpoint Denial of Service: Application 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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