CVE-2025-40205

Kernel memory corruption via undersized file handle

Published Nov 12, 2025 · Updated Aug 5, 2026

Out-of-bounds write in Linux btrfs allows local users to corrupt kernel memory through name_to_handle_at() on affected kernels. btrfs_encode_fh() reports space for eight 32-bit words but writes ten when parent and inode root IDs differ, overrunning the handle by eight bytes. Any local unprivileged user with read access to an already-mounted btrfs filesystem can trigger the write, leading to disclosure, control-flow corruption, or a kernel panic.

CVSS severity7.8
High
EPSS probability0.14%
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 btrfs allows local users to corrupt kernel memory through name_to_handle_at() on affected kernels. btrfs_encode_fh() reports space for eight 32-bit words but writes ten when parent and inode root IDs differ, overrunning the handle by eight bytes. Any local unprivileged user with read access to an already-mounted btrfs filesystem can trigger the write, leading to disclosure, control-flow corruption, or a kernel panic.

The record

CVE
CVE-2025-40205
Published
Nov 12, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.29
  2. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <0276c8582488022f057b4cec21975a5edf079f47
  3. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <361d67276eb8ec6be8f27f4ad6c6090459438fee
  4. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <43143776b0a7604d873d1a6f3e552a00aa930224
  5. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <60de2f55d2aca53e81b4ef2a67d7cc9e1eb677db
  6. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <742b44342204e5dfe3926433823623c1a0c581df
  7. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <d3a9a8e1275eb9b87f006b5562a287aea3f6885f
  8. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <d91f6626133698362bba08fbc04bd72c466806d3
  9. Affected versionversion=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <dff4f9ff5d7f289e4545cc936362e01ed3252742

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.29; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <0276c8582488022f057b4cec21975a5edf079f47; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <361d67276eb8ec6be8f27f4ad6c6090459438fee; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <43143776b0a7604d873d1a6f3e552a00aa930224; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <60de2f55d2aca53e81b4ef2a67d7cc9e1eb677db; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <742b44342204e5dfe3926433823623c1a0c581df; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <d3a9a8e1275eb9b87f006b5562a287aea3f6885f; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <d91f6626133698362bba08fbc04bd72c466806d3; version=be6e8dc0ba84029997075a1ec77b4ddb863cbe15 <dff4f9ff5d7f289e4545cc936362e01ed3252742

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8Linux kernel security teamCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5OracleCVSS: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

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

T1068Exploitation for Privilege Escalation

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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