CVE-2025-39727

Kernel memory corruption via unchecked swap badpage

Published Sep 7, 2025 · Updated May 11, 2026

Out-of-bounds write in affected Linux kernel versions allows local users to corrupt kernel memory through malformed swap bad-page metadata. setup_swap_map accepts bad-page indexes up to last_page, but setup_clusters passes them to inc_cluster_info_page without first ensuring they are below maxpages. Reachability requires local access and activation of a swap area containing an index in that gap; processing it can corrupt kernel memory and interrupt the system.

CVSS severity7.8
High
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

Out-of-bounds write in affected Linux kernel versions allows local users to corrupt kernel memory through malformed swap bad-page metadata. setup_swap_map accepts bad-page indexes up to last_page, but setup_clusters passes them to inc_cluster_info_page without first ensuring they are below maxpages. Reachability requires local access and activation of a swap area containing an index in that gap; processing it can corrupt kernel memory and interrupt the system.

The record

CVE
CVE-2025-39727
Published
Sep 7, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-120, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 7, 2025CVE publishedPublication date reported by the CVE source.
  2. May 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=6.12
  2. Affected versionversion=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <152c1339dc13ad46f1b136e8693de15980750835
  3. Affected versionversion=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <815c528b13f2bb9b3130c13bedeabf2351a68129
  4. Affected versionversion=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <91b370800b3f2b3dda244c0ab06719c4971190a5
  5. Affected versionversion=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <9b01ada580ee84fb319e7ecb5fb5b1f54a9eb799

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <152c1339dc13ad46f1b136e8693de15980750835; version=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <815c528b13f2bb9b3130c13bedeabf2351a68129; version=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <91b370800b3f2b3dda244c0ab06719c4971190a5; version=b843786b0bd01ced7fcdbf3b033d68db2f7c61b2 <9b01ada580ee84fb319e7ecb5fb5b1f54a9eb799

Published CVSS scores

7.8UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
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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