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CVE-2026-64239 (GCVE-0-2026-64239)

Vulnerability from cvelistv5 – Published: 2026-07-24 15:27 – Updated: 2026-07-24 15:27
VLAI
Title
mm/damon/sysfs-schemes: delete tried region in regions_rmdirs()
Summary
In 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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9277d0367ba18ef4bb98bafb1209e715844cdf7e , < c0e37017a452addec873865c94cf7a665663a9b2 (git)
Affected: 9277d0367ba18ef4bb98bafb1209e715844cdf7e , < a5fa42214de55e43d165144727ce9facb9fc6b08 (git)
Affected: 9277d0367ba18ef4bb98bafb1209e715844cdf7e , < 0ba6c05156d9ff9fc6ca22b7690e2eec9eca66f7 (git)
Affected: 9277d0367ba18ef4bb98bafb1209e715844cdf7e , < 2c33177023c92e76806c535ddbffaa3d3fc37777 (git)
Affected: 9277d0367ba18ef4bb98bafb1209e715844cdf7e , < 441f92f7d386b85bad16de49db95a307cba048a2 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-13T17:54:50+00:00",
      "cve": "CVE-2026-64239",
      "id": "CVE-2026-64239",
      "initial_release_date": "2026-07-24T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mm/damon/sysfs-schemes: delete tried region in regions_rmdirs()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64239.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-06T01:08:45Z",
      "cve": "CVE-2026-64239",
      "id": "CVE-2026-64239",
      "initial_release_date": "2026-07-25T00:13:53Z",
      "product_status:known_affected": "131",
      "product_status:known_not_affected": "167",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64239",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64239.json",
      "version": "4"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.