CVE-2026-64399: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-mrp6-592v-c3fh
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CVSS 9.8
Published
Advisory Summary

CVE-2026-64399 is a CRITICAL (CVSS 9.8) security vulnerability vulnerability (General Security Weakness) affecting Software libraries in the Maven ecosystem. Remediation is available in the latest vendor maintenance releases.

CVE-2026-64399 at a Glance

CVE Identifier CVE-2026-64399
GHSA Identifier GHSA-mrp6-592v-c3fh
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification General Security Weakness
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-64399

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-64399, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

In the Linux kernel, the following vulnerability has been resolved: ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data.

References

NVD — CVE-2026-64399 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-64399
git.kernel.org/stable/c/388e4139db... WEB
https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3
git.kernel.org/stable/c/620d133d46... WEB
https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a
git.kernel.org/stable/c/9b9cf7e65c... WEB
https://git.kernel.org/stable/c/9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6
git.kernel.org/stable/c/baae7b3967... WEB
https://git.kernel.org/stable/c/baae7b39673ec21073a25e3d14f8feaada01d5df
git.kernel.org/stable/c/bf460ad595... WEB
https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51
git.kernel.org/stable/c/c917e4522d... WEB
https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe

Frequently Asked Questions

What is CVE-2026-64399?
CVE-2026-64399 is a security vulnerability in Software classified as a security vulnerability vulnerability under General Security Weakness.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-64399?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-64399?
CVE-2026-64399 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-64399?
CVE-2026-64399 is classified under General Security Weakness.
How can I check Maven dependencies for CVE-2026-64399?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
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  "schema_version" : "1.4.0",
  "id" : "GHSA-mrp6-592v-c3fh",
  "modified" : "2026-07-27T06:30:36Z",
  "published" : "2026-07-25T12:31:34Z",
  "aliases" : [ "CVE-2026-64399" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE\n\nThe FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the\ndestination file's data via vfs_clone_file_range() with neither the\nshare-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle\nfp->daccess check that the other write-bearing arms carry. A client can\noverwrite destination data on a read-only share, or from a handle opened\nwith only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp).\nFILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via\nthe clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix;\nrequire FILE_WRITE_DATA since this writes data.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-64399"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a"
  }, {
    "type" : "WEB",
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    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51"
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    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-25T10:17:23Z"
  }
}