CVE-2025-39800

Filesystem metadata corruption via unchecked extent generation

Published Sep 15, 2025 · Updated Sep 15, 2025

Filesystem metadata corruption in btrfs in affected Linux kernel versions allows local users to persist invalid extent metadata. The btrfs_copy_root() path only issues WARN_ON() for an unexpected cloned extent-buffer generation, then continues and commits the transaction instead of returning an error. Exploitation requires local low-privilege access to a mounted btrfs volume through snapshot creation or relocation, and corrupted metadata can compromise filesystem integrity and availability.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Filesystem metadata corruption in btrfs in affected Linux kernel versions allows local users to persist invalid extent metadata. The btrfs_copy_root() path only issues WARN_ON() for an unexpected cloned extent-buffer generation, then continues and commits the transaction instead of returning an error. Exploitation requires local low-privilege access to a mounted btrfs volume through snapshot creation or relocation, and corrupted metadata can compromise filesystem integrity and availability.

The record

CVE
CVE-2025-39800
Published
Sep 15, 2025
Updated
Sep 15, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1565.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 15, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <33e8f24b52d2796b8cfb28c19a1a7dd6476323a8
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4290e34fb87ae556b12c216efd0ae91583446b7a
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4734255ef39b416864139dcda96a387fe5f33a6a
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <da2124719f386b6e5d4d4b1a2e67c440e4d5892f
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4f5bd9251a4cbe55aaa05725c6c3c32ad1f74b3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <33e8f24b52d2796b8cfb28c19a1a7dd6476323a8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4290e34fb87ae556b12c216efd0ae91583446b7a; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4734255ef39b416864139dcda96a387fe5f33a6a; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <da2124719f386b6e5d4d4b1a2e67c440e4d5892f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4f5bd9251a4cbe55aaa05725c6c3c32ad1f74b3

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5NIST NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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