CVE-2026-89755 - Vulnerability Details

- mm/migrate_device: clear stale mapping after freeing swapcache

Description

In the Linux kernel, the following vulnerability has been resolved:

mm/migrate_device: clear stale mapping after freeing swapcache

__migrate_device_pages() reads the folio mapping before calling
folio_free_swap(). When folio_free_swap() succeeds, the folio is removed
from the swap cache, but the saved mapping still points to swap_space.

Passing the stale mapping to folio_migrate_mapping() makes it use the
mapped-folio path for a folio that is no longer in swapcache. It can then
operate on swap_space.i_pages with invalid reference accounting,
eventually triggering a folio reference count BUG.

After a successful split, nr still contains the number of pages in the
original large folio, although each resulting page is now a separate
order-0 folio. Reset nr to 1 so each split folio is processed separately,
including its own swapcache removal and mapping lookup.

Refresh the saved mapping after folio_free_swap() so the current folio
state is used during migration.

Published: 2026-09-11

Score: 7.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The Linux kernel’s memory migration code incorrectly retains a stale swapcache mapping after a folio has been freed, leading to an invalid reference count assertion and a BUG. Based on the description, it is inferred that this flaw could trigger a kernel panic, potentially causing the system to halt abruptly and disrupting all operations on the affected host.

Affected Systems

All Linux kernel releases that compile the mm/migrate_device subsystem are impacted, as the vulnerability resides in kernel code that is present in standard indicates any Linux kernel release; no product‑specific version range is specified, so any kernel build susceptible to this code path is considered at risk until the patch is applied.

Risk and Exploitability

The CVSS score of 7.8 signals high severity. The EPSS of less than 1% indicates a very low likelihood of real‑world exploitation, and the vulnerability is not listed in CISA’s KEV catalog. Based on the description, it is inferred that an attacker would need local privilege or the ability to influence kernel memory layout to trigger the fault, while remote exploitation is unlikely because the flaw requires internal kernel operations.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`df263d9a7dffee94ca5391120ee3b0587efa07f1`	affected	< 4fa91f7bbc4135240b67daac03fc17d9e180a331
`df263d9a7dffee94ca5391120ee3b0587efa07f1`	affected	< 8ffedc6573a665cdc31ebe47eae7b32b78d0df83
`df263d9a7dffee94ca5391120ee3b0587efa07f1`	affected	< 34a00895d032a414830d41106a09329ae6c251b6

Linux

affected

Version	Status	Constraints
`6.6`	affected	—
`0`	unaffected	< 6.6
`6.12.111`	unaffected	≤ 6.12.*
`7.2.4`	unaffected	≤ 7.2.*
`7.3-rc1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[df263d9a7dffee94ca5391120ee3b0587efa07f1,8ffedc6573a665cdc31ebe47eae7b32b78d0df83)`	affected	code_commit	—
`[df263d9a7dffee94ca5391120ee3b0587efa07f1,34a00895d032a414830d41106a09329ae6c251b6)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.6`	affected	generic	—
`[0,6.6)`	unaffected	generic	—
`[7.2.4,7.3.0)`	unaffected	semver	—
`[7.3-rc1,*]`	unaffected	semver	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Install the latest kernel update that includes the update to __migrate_device_pages and the refreshed mapping logic after folio_free_swap.
If a kernel update cannot be applied immediately, reduce the use of high‑throughput memory migration operations involving swapcache, such as limiting voluminous page migrations.
Enable logging and monitor dmesg or system journal entries for BUG or oops messages that indicate a bad reference count or kernel panic.

Generated by OpenCVE AI on September 15, 2026 at 19:08 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DSA	DSA-6528-1	linux security update

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00173.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/34a00895d032a414830d41106a09329ae6c251b6
https://git.kernel.org/stable/c/4fa91f7bbc4135240b67daac03fc17d9e180a331
https://git.kernel.org/stable/c/8ffedc6573a665cdc31ebe47eae7b32b78d0df83
https://nvd.nist.gov/vuln/detail/CVE-2026-89755
https://www.cve.org/CVERecord?id=CVE-2026-89755

History

Mon, 21 Sep 2026 13:30:00 +0000

Type	Values Removed	Values Added
References		https://git.kernel.org/stable/c/4fa91f7bbc4135240b67daac03fc17d9e180a331

Sun, 13 Sep 2026 06:45:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 4.1, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H'}`	cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Sat, 12 Sep 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-825
References		https://nvd.nist.gov/vuln/detail/CVE-2026-89755 https://www.cve.org/CVERecord?id=CVE-2026-89755
Metrics	threat_severity `None`	cvssV3_1 `{'score': 4.1, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Fri, 11 Sep 2026 23:45:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: mm/migrate_device: clear stale mapping after freeing swapcache __migrate_device_pages() reads the folio mapping before calling folio_free_swap(). When folio_free_swap() succeeds, the folio is removed from the swap cache, but the saved mapping still points to swap_space. Passing the stale mapping to folio_migrate_mapping() makes it use the mapped-folio path for a folio that is no longer in swapcache. It can then operate on swap_space.i_pages with invalid reference accounting, eventually triggering a folio reference count BUG. After a successful split, nr still contains the number of pages in the original large folio, although each resulting page is now a separate order-0 folio. Reset nr to 1 so each split folio is processed separately, including its own swapcache removal and mapping lookup. Refresh the saved mapping after folio_free_swap() so the current folio state is used during migration.
Title		mm/migrate_device: clear stale mapping after freeing swapcache
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/34a00895d032a414830d41106a09329ae6c251b6 https://git.kernel.org/stable/c/8ffedc6573a665cdc31ebe47eae7b32b78d0df83

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-09-11T19:46:58.295Z

Updated: 2026-09-21T13:14:58.853Z

Reserved: 2026-09-11T19:38:34.763Z

Link: CVE-2026-89755

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-09-11T20:20:06.533

Modified: 2026-09-21T14:17:26.320

Link: CVE-2026-89755

Redhat

Severity : Moderate

Publid Date: 2026-09-11T19:46:58Z

Links: CVE-2026-89755 - Bugzilla

OpenCVE Enrichment

Updated: 2026-09-15T19:15:16Z

Weaknesses

CWE-825
Expired Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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