CVE-2026-72412
s390/mm: Fix handling of _PAGE_UNUSED pte bit
Description
In the Linux kernel, the following vulnerability has been resolved: s390/mm: Fix handling of _PAGE_UNUSED pte bit The _PAGE_UNUSED softbit should not really be lying around. Its sole purpose is to signal to try_to_unmap_one() and try_to_migrate_one() that the page can be discarded instead of being moved / swapped. KVM has no way to know why a page is being unmapped, so it sets the bit on userspace ptes corresponding to unused guest pages every time they get unmapped. KVM has no reasonable way to clear the bit once the page is in use again. While set_ptes() checks and clears the bit, other paths that set new ptes did not. This led to used pages being thrown out as if they were unused, causing guest corruption. Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in set_pte(), i.e. whenever a present pte is getting set. The check in set_ptes() is then redundant and can be removed. Also fix gmap_helper_try_set_pte_unused() to only set the bit if the pte is present; the _PAGE_UNUSED bit is only defined for present ptes and thus should not be set for non-present ptes.
INFO
Published Date :
Aug. 15, 2026, 6:22 a.m.
Last Modified :
Aug. 17, 2026, 6:19 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Update the Linux kernel to the latest version.
- Ensure all present page table entries are correctly updated.
- Clear the _PAGE_UNUSED bit for present page table entries.
- Validate guest page unmapping and remapping logic.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-72412.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/d4bb00704a66024502261fa7a523c07420249fea | |
| https://git.kernel.org/stable/c/fda07c8e4b54b9105f1ca73f0adea7b244d405f4 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-72412 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-72412
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-72412 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-72412 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'fda07c8e4b54b9105f1ca73f0adea7b244d405f4', 'versionType': 'git'}, {'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'd4bb00704a66024502261fa7a523c07420249fea', 'versionType': 'git'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'fda07c8e4b54b9105f1ca73f0adea7b244d405f4', 'versionType': 'git'}, {'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'd4bb00704a66024502261fa7a523c07420249fea', 'versionType': 'git'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'fda07c8e4b54b9105f1ca73f0adea7b244d405f4', 'versionType': 'git'}, {'status': 'affected', 'version': 'c98175b7917fa81cd499b1527c4a57fd7d36711e', 'lessThan': 'd4bb00704a66024502261fa7a523c07420249fea', 'versionType': 'git'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['arch/s390/include/asm/pgtable.h', 'arch/s390/mm/gmap_helpers.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: s390/mm: Fix handling of _PAGE_UNUSED pte bit The _PAGE_UNUSED softbit should not really be lying around. Its sole purpose is to signal to try_to_unmap_one() and try_to_migrate_one() that the page can be discarded instead of being moved / swapped. KVM has no way to know why a page is being unmapped, so it sets the bit on userspace ptes corresponding to unused guest pages every time they get unmapped. KVM has no reasonable way to clear the bit once the page is in use again. While set_ptes() checks and clears the bit, other paths that set new ptes did not. This led to used pages being thrown out as if they were unused, causing guest corruption. Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in set_pte(), i.e. whenever a present pte is getting set. The check in set_ptes() is then redundant and can be removed. Also fix gmap_helper_try_set_pte_unused() to only set the bit if the pte is present; the _PAGE_UNUSED bit is only defined for present ptes and thus should not be set for non-present ptes. Added Reference https://git.kernel.org/stable/c/d4bb00704a66024502261fa7a523c07420249fea Added Reference https://git.kernel.org/stable/c/fda07c8e4b54b9105f1ca73f0adea7b244d405f4