CVE-2026-45256: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-hvc9-hvw8-q2fx
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CVSS 5.5
CWE-269
Published
Advisory Summary

CVE-2026-45256 is a MODERATE (CVSS 5.5) security vulnerability vulnerability (CWE-269: Improper Privilege Management) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-45256 at a Glance

CVE Identifier CVE-2026-45256
GHSA Identifier GHSA-hvc9-hvw8-q2fx
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-269: Improper Privilege Management
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.5

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

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

How to Fix CVE-2026-45256

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-2026-45256, 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 CWE-269: Improper Privilege Management, where the product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. 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

When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the operation was permitted but did not check the result before delivering the signal. The signal was sent even when the permission check failed. The system call returned the resulting error to the caller, but by then the signal had already been delivered. The missing check allows an unprivileged local user who knows or can guess a target's process and thread IDs to send any signal to a process they would not normally be permitted to signal, including processes owned by other users or by root. The same check enforces jail boundaries, so a jailed process can signal processes on the host or in other jails. Thread IDs are allocated globally and sequentially, and so can be discovered by brute force with no visibility into the target. An attacker can stop or terminate arbitrary processes, including critical system daemons, resulting in a Denial of Service (DoS).

References

NVD — CVE-2026-45256 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45256
Software Security Information SECURITY
https://security.freebsd.org/advisories/FreeBSD-SA-26:25.thr.asc

Frequently Asked Questions

What is CVE-2026-45256?
CVE-2026-45256 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-269: Improper Privilege Management.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-45256?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-45256?
CVE-2026-45256 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-45256?
CVE-2026-45256 is classified under CWE-269: Improper Privilege Management (The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.).
How can I check Maven dependencies for CVE-2026-45256?
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 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hvc9-hvw8-q2fx",
  "modified" : "2026-06-26T18:33:53Z",
  "published" : "2026-06-26T15:32:15Z",
  "aliases" : [ "CVE-2026-45256" ],
  "details" : "When used to deliver a signal to a specific thread, thr_kill2(2) called p_cansignal() to determine whether the operation was permitted but did not check the result before delivering the signal.  The signal was sent even when the permission check failed.  The system call returned the resulting error to the caller, but by then the signal had already been delivered.\n\nThe missing check allows an unprivileged local user who knows or can guess a target's process and thread IDs to send any signal to a process they would not normally be permitted to signal, including processes owned by other users or by root.  The same check enforces jail boundaries, so a jailed process can signal processes on the host or in other jails.  Thread IDs are allocated globally and sequentially, and so can be discovered by brute force with no visibility into the target.\n\nAn attacker can stop or terminate arbitrary processes, including critical system daemons, resulting in a Denial of Service (DoS).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45256"
  }, {
    "type" : "WEB",
    "url" : "https://security.freebsd.org/advisories/FreeBSD-SA-26:25.thr.asc"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-269" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-06-26T15:16:39Z"
  }
}