CVE-2026-63909: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-77x3-ghg7-w5wj
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CVSS 8.1
Published
Advisory Summary

CVE-2026-63909 is a HIGH (CVSS 8.1) security vulnerability vulnerability (General Security Weakness) affecting Software libraries in the Maven ecosystem. Remediation is available in the latest vendor maintenance releases.

CVE-2026-63909 at a Glance

CVE Identifier CVE-2026-63909
GHSA Identifier GHSA-77x3-ghg7-w5wj
Severity HIGH
CVSS v3.1 Base Score 8.1
CWE Classification General Security Weakness
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.1

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

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

How to Fix CVE-2026-63909

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-2026-63909, 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: OOB read regression in smb_check_perm_dacl() ACE-walk loops Commit d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()") introduced a transposed bounds check: if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE) Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates to `aces_size < 0`. Because `aces_size` is always non-negative, this check becomes dead code and never breaks the loop. Worse, that commit removed the old 4-byte guard, meaning the loop now reads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation during subsequent SMB2_CREATE operations. Fix this by properly transposing the comparison to require at least 16 bytes (8-byte offset + 8-byte SID base), matching the correct form used in smb_inherit_dacl().

References

NVD — CVE-2026-63909 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63909
git.kernel.org/stable/c/0e60dafe97... WEB
https://git.kernel.org/stable/c/0e60dafe97eca61721f3db456f97d97a80c6c8ae
git.kernel.org/stable/c/0fe08c5776... WEB
https://git.kernel.org/stable/c/0fe08c5776a798f46df1fd74b331be26bdd644d6
git.kernel.org/stable/c/4f7c131d2b... WEB
https://git.kernel.org/stable/c/4f7c131d2bdd7cd64b96f60d10be5ea72253f520
git.kernel.org/stable/c/5500ba1d41... WEB
https://git.kernel.org/stable/c/5500ba1d410aed1eded3eb04a76b10cfb4409334
git.kernel.org/stable/c/94215d55b0... WEB
https://git.kernel.org/stable/c/94215d55b09445993929f4fc966061d61de74929
git.kernel.org/stable/c/d333af32e4... WEB
https://git.kernel.org/stable/c/d333af32e4451285e427f2d9c29de3a39f6f6d48
git.kernel.org/stable/c/f6324b4240... WEB
https://git.kernel.org/stable/c/f6324b4240cf0b26a84c33f68a1222d727ff4af2

Frequently Asked Questions

What is CVE-2026-63909?
CVE-2026-63909 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-2026-63909?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-63909?
CVE-2026-63909 has a CVSS v3.1 base score of 8.1 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H.
What CWE is associated with CVE-2026-63909?
CVE-2026-63909 is classified under General Security Weakness.
How can I check Maven dependencies for CVE-2026-63909?
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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  "id" : "GHSA-77x3-ghg7-w5wj",
  "modified" : "2026-07-20T15:31:50Z",
  "published" : "2026-07-19T18:31:45Z",
  "aliases" : [ "CVE-2026-63909" ],
  "details" : "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: OOB read regression in smb_check_perm_dacl() ACE-walk loops\n\nCommit d07b26f39246 (\"ksmbd: require minimum ACE size in\nsmb_check_perm_dacl()\") introduced a transposed bounds check:\n\n    if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE)\n\nSince offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates\nto `aces_size < 0`. Because `aces_size` is always non-negative, this\ncheck becomes dead code and never breaks the loop.\n\nWorse, that commit removed the old 4-byte guard, meaning the loop now\nreads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This\nre-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation\nduring subsequent SMB2_CREATE operations.\n\nFix this by properly transposing the comparison to require at least\n16 bytes (8-byte offset + 8-byte SID base), matching the correct form\nused in smb_inherit_dacl().",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-63909"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/0e60dafe97eca61721f3db456f97d97a80c6c8ae"
  }, {
    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/0fe08c5776a798f46df1fd74b331be26bdd644d6"
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    "type" : "WEB",
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    "type" : "WEB",
    "url" : "https://git.kernel.org/stable/c/f6324b4240cf0b26a84c33f68a1222d727ff4af2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-19T16:17:08Z"
  }
}