GHSA-V8WJ-8J36-23J2
Vulnerability from github – Published: 2026-07-24 18:31 – Updated: 2026-08-13 18:31In the Linux kernel, the following vulnerability has been resolved:
mm/damon/sysfs-schemes: delete tried region in regions_rmdirs()
DAMON sysfs maintains the DAMOS tried region directory objects via a linked list. When the user requests refresh of the directories, DAMON sysfs removes all the region directories first, and then generate updated regions directory on the empty space. The removal function (damon_sysfs_scheme_regions_rm_dirs()) only puts the kobj objects. Deletion of the container region object from the linked list is done inside the kobj release callback function.
If somehow the callback invocation is delayed, the list will contain regions list that gonna be freed. If the updated region directories creation is started in this situation, the list can be corrupted and use-after-free can happen.
Because the kobj objects are managed by only DAMON sysfs, the issue cannot happen in normal situation. But, such delays can be made on kernels that built with CONFIG_DEBUG_KOBJECT_RELEASE. On the kernel, the issue can indeed be reproduced like below.
# damo start --damos_action stat
# cd /sys/kernel/mm/damon/admin/kdamonds/0/
# for i in {1..10}; do echo update_schemes_tried_regions > state; done
# dmesg | grep underflow
[ 89.296152] refcount_t: underflow; use-after-free.
Fix the issue by removing the region object from the list when decrementing the reference count.
Also update damos_sysfs_populate_region_dir() to add the region object to the list only after the kobject_init_and_add() is success, so that fail of kobject_init_and_add() is not leaving the deallocated object on the list.
The issue was discovered [1] by Sashiko.
{
"affected": [],
"aliases": [
"CVE-2026-64239"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-24T16:16:53Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/damon/sysfs-schemes: delete tried region in regions_rmdirs()\n\nDAMON sysfs maintains the DAMOS tried region directory objects via a\nlinked list. When the user requests refresh of the directories, DAMON\nsysfs removes all the region directories first, and then generate updated\nregions directory on the empty space. The removal function\n(damon_sysfs_scheme_regions_rm_dirs()) only puts the kobj objects. \nDeletion of the container region object from the linked list is done\ninside the kobj release callback function.\n\nIf somehow the callback invocation is delayed, the list will contain\nregions list that gonna be freed. If the updated region directories\ncreation is started in this situation, the list can be corrupted and\nuse-after-free can happen.\n\nBecause the kobj objects are managed by only DAMON sysfs, the issue cannot\nhappen in normal situation. But, such delays can be made on kernels that\nbuilt with CONFIG_DEBUG_KOBJECT_RELEASE. On the kernel, the issue can\nindeed be reproduced like below.\n\n # damo start --damos_action stat\n # cd /sys/kernel/mm/damon/admin/kdamonds/0/\n # for i in {1..10}; do echo update_schemes_tried_regions \u003e state; done\n # dmesg | grep underflow\n [ 89.296152] refcount_t: underflow; use-after-free.\n\nFix the issue by removing the region object from the list when\ndecrementing the reference count.\n\nAlso update damos_sysfs_populate_region_dir() to add the region object to\nthe list only after the kobject_init_and_add() is success, so that fail of\nkobject_init_and_add() is not leaving the deallocated object on the list.\n\nThe issue was discovered [1] by Sashiko.",
"id": "GHSA-v8wj-8j36-23j2",
"modified": "2026-08-13T18:31:10Z",
"published": "2026-07-24T18:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64239"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0ba6c05156d9ff9fc6ca22b7690e2eec9eca66f7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2c33177023c92e76806c535ddbffaa3d3fc37777"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/441f92f7d386b85bad16de49db95a307cba048a2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a5fa42214de55e43d165144727ce9facb9fc6b08"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c0e37017a452addec873865c94cf7a665663a9b2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
How durations are calculated
Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.
Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.
Loading timeline…
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.