CVE-2026-64294
mm: do file ownership checks with the proper mount idmap
Description
In the Linux kernel, the following vulnerability has been resolved: mm: do file ownership checks with the proper mount idmap Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara.
INFO
Published Date :
July 25, 2026, 10:17 a.m.
Last Modified :
Aug. 17, 2026, 5:17 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 | MEDIUM | [email protected] |
Solution
- Apply the provided Linux kernel patches.
- Update the Linux kernel to a fixed version.
- Verify the idmap checks are correctly implemented.
- Test file permission checks after update.
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-2026-64294.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-64294 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-2026-64294
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-2026-64294 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-64294 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 Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '744b23aa430d52f5c8e4dbff7d71496d6643bed2', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '8344bdf0629457e532797b42d9d2bbf2a2900bbf', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '5c942ad7df75925ee166e7f0fb36892d8dde376b', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '04ba248d02d9eaa3d9077b00a6134caa75fa3e90', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': 'e187bc02f8fa4226d62814592cf064ee4557c470', 'versionType': 'git'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.96', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.39', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.4', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '744b23aa430d52f5c8e4dbff7d71496d6643bed2', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '8344bdf0629457e532797b42d9d2bbf2a2900bbf', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '5c942ad7df75925ee166e7f0fb36892d8dde376b', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '04ba248d02d9eaa3d9077b00a6134caa75fa3e90', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': 'e187bc02f8fa4226d62814592cf064ee4557c470', 'versionType': 'git'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.96', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.39', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.4', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'affected'}] -
Initial Analysis by [email protected]
Aug. 12, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.96 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.39 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.1.4 *cpe:2.3:o:linux:linux_kernel:7.2:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.2:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.12 up to (excluding) 6.6.145 Added Reference Type kernel.org: https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470 Types: Patch -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 25, 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': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '744b23aa430d52f5c8e4dbff7d71496d6643bed2', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '8344bdf0629457e532797b42d9d2bbf2a2900bbf', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '5c942ad7df75925ee166e7f0fb36892d8dde376b', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': '04ba248d02d9eaa3d9077b00a6134caa75fa3e90', 'versionType': 'git'}, {'status': 'affected', 'version': '9caccd41541a6f7d6279928d9f971f6642c361af', 'lessThan': 'e187bc02f8fa4226d62814592cf064ee4557c470', 'versionType': 'git'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5.12'}, {'status': 'unaffected', 'version': '0', 'lessThan': '5.12', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.145', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.96', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.39', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.4', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['include/linux/fs.h', 'mm/filemap.c', 'mm/madvise.c', 'mm/mincore.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: mm: do file ownership checks with the proper mount idmap Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara. Added Reference https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90 Added Reference https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b Added Reference https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2 Added Reference https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf Added Reference https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470