CVE-2026-78159: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-9c57-9fxg-8x9j
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CVSS 9.8
CWE-94
Published
Advisory Summary

CVE-2026-78159 is a CRITICAL (CVSS 9.8) security vulnerability vulnerability (CWE-94: Improper Control of Generation of Code ('Code Injection')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-78159 at a Glance

CVE Identifier CVE-2026-78159
GHSA Identifier GHSA-9c57-9fxg-8x9j
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-94: Improper Control of Generation of Code ('Code Injection')
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-2026-78159

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-2026-78159, 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-94: Improper Control of Generation of Code ('Code Injection'), where the product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. 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

The The Events Calendar plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 6.17.3 via the parse_array function. This is due to insufficient validation of the widget 'classes' map, allowing a plain-array payload to bypass the is_safe_widget_instance() object check and reach the callable-invocation sink in Element_Classes::parse_array(). This makes it possible for unauthenticated attackers to execute code on the server. Exploitation requires that the targeted site has comments enabled on tribe_events posts and that at least one comment containing a crafted wp:legacy-widget block has been submitted, as the attack chain is triggered when do_blocks() processes the single-event HTML including the comment area.

References

NVD — CVE-2026-78159 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-78159
plugins.trac.wordpress.org/browser/the-events-... WEB
https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/common/src/Tribe/Utils/Element_Classes.php#L211
plugins.trac.wordpress.org/browser/the-events-... WEB
https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/Tribe/Views/V2/Template_Bootstrap.php#L214
plugins.trac.wordpress.org/browser/the-events-... WEB
https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/Tribe/Views/V2/Widgets/Service_Provider.php#L279
plugins.trac.wordpress.org/browser/the-events-... WEB
https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/views/v2/components/messages.php#L30
plugins.trac.wordpress.org/changeset WEB
https://plugins.trac.wordpress.org/changeset?reponame=&old=3667866%40the-events-calendar&new=3667866%40the-events-calendar
plugins.trac.wordpress.org/changeset WEB
https://plugins.trac.wordpress.org/changeset?reponame=&old=3667867%40the-events-calendar&new=3667867%40the-events-calendar
www.wordfence.com/threat-intel/vulner... WEB
https://www.wordfence.com/threat-intel/vulnerabilities/id/cc2ccfeb-6df6-4fee-96a5-94f8dd131f7c?source=cve

Frequently Asked Questions

What is CVE-2026-78159?
CVE-2026-78159 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-94: Improper Control of Generation of Code ('Code Injection').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-78159?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-78159?
CVE-2026-78159 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-2026-78159?
CVE-2026-78159 is classified under CWE-94: Improper Control of Generation of Code ('Code Injection') (The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.).
How can I check Maven dependencies for CVE-2026-78159?
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-9c57-9fxg-8x9j",
  "modified" : "2026-09-12T09:33:35Z",
  "published" : "2026-09-12T09:33:35Z",
  "aliases" : [ "CVE-2026-78159" ],
  "details" : "The The Events Calendar plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 6.17.3 via the parse_array function. This is due to insufficient validation of the widget 'classes' map, allowing a plain-array payload to bypass the is_safe_widget_instance() object check and reach the callable-invocation sink in Element_Classes::parse_array(). This makes it possible for unauthenticated attackers to execute code on the server. Exploitation requires that the targeted site has comments enabled on tribe_events posts and that at least one comment containing a crafted wp:legacy-widget block has been submitted, as the attack chain is triggered when do_blocks() processes the single-event HTML including the comment area.",
  "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-2026-78159"
  }, {
    "type" : "WEB",
    "url" : "https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/common/src/Tribe/Utils/Element_Classes.php#L211"
  }, {
    "type" : "WEB",
    "url" : "https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/Tribe/Views/V2/Template_Bootstrap.php#L214"
  }, {
    "type" : "WEB",
    "url" : "https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/Tribe/Views/V2/Widgets/Service_Provider.php#L279"
  }, {
    "type" : "WEB",
    "url" : "https://plugins.trac.wordpress.org/browser/the-events-calendar/tags/6.17.3/src/views/v2/components/messages.php#L30"
  }, {
    "type" : "WEB",
    "url" : "https://plugins.trac.wordpress.org/changeset?reponame=&old=3667866%40the-events-calendar&new=3667866%40the-events-calendar"
  }, {
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    "url" : "https://plugins.trac.wordpress.org/changeset?reponame=&old=3667867%40the-events-calendar&new=3667867%40the-events-calendar"
  }, {
    "type" : "WEB",
    "url" : "https://www.wordfence.com/threat-intel/vulnerabilities/id/cc2ccfeb-6df6-4fee-96a5-94f8dd131f7c?source=cve"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-94" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-12T08:16:24Z"
  }
}