CVE-2026-46121 - Vulnerability Details

- mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock

Description

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

mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock

Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path".

Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race
with their writes, results in use-after-free. Fix those.

This patch (of 2):

damon_sysfs_scheme_filter->mmecg_path can be read and written by users,
via DAMON sysfs memcg_path file. It can also be indirectly read, for the
parameters {on,off}line committing to DAMON. The reads for parameters
committing are protected by damon_sysfs_lock to avoid the sysfs files
being destroyed while any of the parameters are being read. But the
user-driven direct reads and writes are not protected by any lock, while
the write is deallocating the memcg_path-pointing buffer. As a result,
the readers could read the already freed buffer (user-after-free). Note
that the user-reads don't race when the same open file is used by the
writer, due to kernfs's open file locking. Nonetheless, doing the reads
and writes with separate open files would be common. Fix it by protecting
both the user-direct reads and writes with damon_sysfs_lock.

Published: 2026-05-28

Score: 7.0 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability is a race condition between reads and writes to the 'memcg_path' and 'path' files in the DAMON sysfs interface. A write operation deallocates the buffer that holds the path while a separate read may access the freed memory, resulting in a use‑after‑free. This can lead to kernel memory corruption but does not provide an immediate code execution path.

Affected Systems

The flaw exists in the Linux kernel for all releases for which the patch has not yet been applied. No specific kernel versions are listed as affected; the vulnerability is identified generally across the Linux platform.

Risk and Exploitability

The CVSS score is 7.0, indicating high severity, and the EPSS score is < 1%, which suggests a low current exploitation probability. The vulnerability is not listed in the CISA KEV catalog. Based on the description, the attack requires a local user with the ability to read and write the /sys/kernel/damon/memcg_path file, typically meaning root or a user with elevated rights. The race condition makes the issue exploitable when reads and writes are performed via separate open file descriptors, which is a common usage pattern. If a successful attempt is made, it could lead to kernel memory corruption, potentially disrupting system operation or compromising system integrity.

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
`490a43d07f1663d827e802720d30cbc0494e4f81`	affected	< b1e9f2d5870776347edef927f9bb3ea19b8e3abb
`c5d5b0047b0c0f304608f3824139f7bd34c48413`	affected	< c88802d0e8edd14b6cd2daf3000f99adbc4c85c5
`4f489fe6afb395dbc79840efa3c05440b760d883`	affected	< eafd6f5372d29b0dd213799b92c2c9c7ad31d7da
`4f489fe6afb395dbc79840efa3c05440b760d883`	affected	< baecc45ad60e621ef14d6c1e7f41ef36bbfdf910
`4f489fe6afb395dbc79840efa3c05440b760d883`	affected	< 1e68eb96e8beb1abefd12dd22c5637795d8a877e
`4a158ac0538dd5695eeaa00aa0720d711f3e4ef1`	affected	—
`6.6.96`	affected	< 6.6.140
`6.12.36`	affected	< 6.12.88
`6.15.5`	affected	< 6.16

Linux

affected

Version	Status	Constraints
`6.16`	affected	—
`0`	unaffected	< 6.16
`6.6.140`	unaffected	≤ 6.6.*
`6.12.88`	unaffected	≤ 6.12.*
`6.18.30`	unaffected	≤ 6.18.*
`7.0.7`	unaffected	≤ 7.0.*
`7.1`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[490a43d07f1663d827e802720d30cbc0494e4f81,b1e9f2d5870776347edef927f9bb3ea19b8e3abb)`	affected	code_commit	—
`[c5d5b0047b0c0f304608f3824139f7bd34c48413,c88802d0e8edd14b6cd2daf3000f99adbc4c85c5)`	affected	code_commit	—
`[4f489fe6afb395dbc79840efa3c05440b760d883,baecc45ad60e621ef14d6c1e7f41ef36bbfdf910)`	affected	code_commit	—
`[4f489fe6afb395dbc79840efa3c05440b760d883,b1e9f2d5870776347edef927f9bb3ea19b8e3abb)`	affected	code_commit	—
`[4f489fe6afb395dbc79840efa3c05440b760d883,eafd6f5372d29b0dd213799b92c2c9c7ad31d7da)`	affected	code_commit	—
`[4f489fe6afb395dbc79840efa3c05440b760d883,1e68eb96e8beb1abefd12dd22c5637795d8a877e)`	affected	code_commit	—
`[4a158ac0538dd5695eeaa00aa0720d711f3e4ef1,*]`	affected	code_commit	—
`[6.6.96,6.6.140)`	affected	semver	—
`[6.12.36,6.12.88)`	affected	semver	—
`[6.15.5,6.16)`	affected	semver	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.16`	affected	generic	—
`[0,6.16)`	unaffected	semver	—
`[6.6.140,7.0.0)`	unaffected	semver	—
`[6.12.88,6.13.0)`	unaffected	semver	—
`[6.18.30,6.19.0)`	unaffected	semver	—
`[7.0.7,7.1.0)`	unaffected	semver	—
`[7.1-rc2,*]`	unaffected	generic	—

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Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Upgrade the Linux kernel to a version that incorporates the damon_sysfs_lock fix, such as the latest stable release of the 6.x series.
If an upgrade is not immediately possible, cherry–pick the commits identified in the provided git links (c/1e68eb96, c/b1e9f2d5, c/baecc45, c/c88802d0, c/eafd6f53) into your kernel source, rebuild, and reboot.
As a temporary safeguard when you cannot modify the kernel, restrict write access to /sys/kernel/damon/memcg_path by setting file permissions to root only or by disabling the DAMON sysfs interface if it is not required for your workloads.

Generated by OpenCVE AI on May 29, 2026 at 02:25 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

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 0.00168.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/1e68eb96e8beb1abefd12dd22c5637795d8a877e
https://git.kernel.org/stable/c/b1e9f2d5870776347edef927f9bb3ea19b8e3abb
https://git.kernel.org/stable/c/baecc45ad60e621ef14d6c1e7f41ef36bbfdf910
https://git.kernel.org/stable/c/c88802d0e8edd14b6cd2daf3000f99adbc4c85c5
https://git.kernel.org/stable/c/eafd6f5372d29b0dd213799b92c2c9c7ad31d7da
https://lore.kernel.org/linux-cve-announce/2026052815-CVE-2026-46121-1535@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2026-46121
https://www.cve.org/CVERecord?id=CVE-2026-46121

History

Fri, 29 May 2026 00:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-367
References		https://lore.kernel.org/linux-cve-announce/2026052815-CVE-2026-46121-1535@gregkh/T https://nvd.nist.gov/vuln/detail/CVE-2026-46121 https://www.cve.org/CVERecord?id=CVE-2026-46121
Metrics	threat_severity `None`	cvssV3_1 `{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}` threat_severity `Moderate`

Thu, 28 May 2026 11:45:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-416

Thu, 28 May 2026 10:15:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock Patch series "mm/damon/sysfs-schemes: fix use-after-free for [memcg_]path". Reads of 'memcg_path' and 'path' files in DAMON sysfs interface could race with their writes, results in use-after-free. Fix those. This patch (of 2): damon_sysfs_scheme_filter->mmecg_path can be read and written by users, via DAMON sysfs memcg_path file. It can also be indirectly read, for the parameters {on,off}line committing to DAMON. The reads for parameters committing are protected by damon_sysfs_lock to avoid the sysfs files being destroyed while any of the parameters are being read. But the user-driven direct reads and writes are not protected by any lock, while the write is deallocating the memcg_path-pointing buffer. As a result, the readers could read the already freed buffer (user-after-free). Note that the user-reads don't race when the same open file is used by the writer, due to kernfs's open file locking. Nonetheless, doing the reads and writes with separate open files would be common. Fix it by protecting both the user-direct reads and writes with damon_sysfs_lock.
Title		mm/damon/sysfs-schemes: protect memcg_path kfree() with damon_sysfs_lock
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/1e68eb96e8beb1abefd12dd22c5637795d8a877e https://git.kernel.org/stable/c/b1e9f2d5870776347edef927f9bb3ea19b8e3abb https://git.kernel.org/stable/c/baecc45ad60e621ef14d6c1e7f41ef36bbfdf910 https://git.kernel.org/stable/c/c88802d0e8edd14b6cd2daf3000f99adbc4c85c5 https://git.kernel.org/stable/c/eafd6f5372d29b0dd213799b92c2c9c7ad31d7da

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-05-28T09:35:36.292Z

Updated: 2026-06-14T17:55:59.503Z

Reserved: 2026-05-13T15:03:33.098Z

Link: CVE-2026-46121

Vulnrichment

No data.

NVD

Status : Awaiting Analysis

Published: 2026-05-28T10:16:27.600

Modified: 2026-05-28T13:44:01.663

Link: CVE-2026-46121

Redhat

Severity : Moderate

Publid Date: 2026-05-28T00:00:00Z

Links: CVE-2026-46121 - Bugzilla

OpenCVE Enrichment

Updated: 2026-05-29T02:30:33Z

Weaknesses

CWE-367
Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-416
Use After Free

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Subscriptions

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