CVE-2026-87830: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-66vg-36xv-j6x4
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CVSS 9.1
CWE-917
Published
Advisory Summary

CVE-2026-87830 is a CRITICAL (CVSS 9.1) security vulnerability vulnerability (CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product constructs all or part of an expression language (el) statement in a framework such as a java server page (jsp) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended el statement before it is executed.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-87830 at a Glance

CVE Identifier CVE-2026-87830
GHSA Identifier GHSA-66vg-36xv-j6x4
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.1

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:N).

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 None (A:N)

How to Fix CVE-2026-87830

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-2026-87830, 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-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection'), where the product constructs all or part of an expression language (el) statement in a framework such as a java server page (jsp) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended el statement before it is executed. 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 StAX streaming WS-SecurityPolicy validator, certain relative or unsupported XPath expressions can be converted into paths that never match the actual XML element path. A remote SOAP peer may therefore send a required element without the expected signature or encryption. Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.

References

NVD — CVE-2026-87830 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-87830
lists.apache.org/thread.html/lwlozb1... WEB
https://lists.apache.org/thread.html/lwlozb1x20d16f9dnyvoygc9rrhzq2vn
Software Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/09/30/9

Frequently Asked Questions

What is CVE-2026-87830?
CVE-2026-87830 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-87830?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-87830?
CVE-2026-87830 has a CVSS v3.1 base score of 9.1 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-87830?
CVE-2026-87830 is classified under CWE-917: Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') (The product constructs all or part of an expression language (EL) statement in a framework such as a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.).
How can I check Maven dependencies for CVE-2026-87830?
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-66vg-36xv-j6x4",
  "modified" : "2026-09-30T21:32:05Z",
  "published" : "2026-09-30T12:35:18Z",
  "aliases" : [ "CVE-2026-87830" ],
  "details" : "In the StAX streaming WS-SecurityPolicy validator, certain relative or unsupported XPath expressions can be converted into paths that never match the actual XML element path. A remote SOAP peer may therefore send a required element without the expected signature or encryption.\nUsers are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-87830"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/lwlozb1x20d16f9dnyvoygc9rrhzq2vn"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/09/30/9"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-917" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-30T12:17:14Z"
  }
}