CVE-2026-64239 Vulnerability Analysis & Exploit Details

CVE-2026-64239
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-64239 Details

Status: Received on 24 Jul 2026, 16:16 UTC

Published on: 24 Jul 2026, 16:16 UTC

CVSS Release:

CVE-2026-64239 Vulnerability Summary

CVE-2026-64239: 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.

Assessing the Risk of CVE-2026-64239

Access Complexity Graph

The exploitability of CVE-2026-64239 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-64239

No exploitability data is available for CVE-2026-64239.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-64239, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-64239, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-64239 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-64239 does not impact data integrity.
  • Availability: None
    CVE-2026-64239 does not affect system availability.

CVE-2026-64239 References

External References

CWE Common Weakness Enumeration

Unknown

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