CVE-2026-76504: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-xqjc-v467-8fvf
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CVSS 9.8
CWE-177
Published
Advisory Summary

CVE-2026-76504 is a CRITICAL (CVSS 9.8) security vulnerability vulnerability (CWE-177: Improper Handling of URL Encoding (Hex Encoding)) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not properly handle when all or part of an input has been url encoded.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-76504 at a Glance

CVE Identifier CVE-2026-76504
GHSA Identifier GHSA-xqjc-v467-8fvf
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-177: Improper Handling of URL Encoding (Hex Encoding)
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-2026-76504

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-2026-76504, 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-177: Improper Handling of URL Encoding (Hex Encoding), where the product does not properly handle when all or part of an input has been url encoded. 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

A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user. This vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user.

References

NVD — CVE-2026-76504 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-76504
Software Security Information SECURITY
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU
www.cisa.gov/known-exploited-vul... WEB
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76504

Frequently Asked Questions

What is CVE-2026-76504?
CVE-2026-76504 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-177: Improper Handling of URL Encoding (Hex Encoding).
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-76504?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-76504?
CVE-2026-76504 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-2026-76504?
CVE-2026-76504 is classified under CWE-177: Improper Handling of URL Encoding (Hex Encoding) (The product does not properly handle when all or part of an input has been URL encoded.).
How can I check Maven dependencies for CVE-2026-76504?
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-xqjc-v467-8fvf",
  "modified" : "2026-09-30T18:33:25Z",
  "published" : "2026-09-30T15:31:25Z",
  "aliases" : [ "CVE-2026-76504" ],
  "details" : "A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user.\n\nThis vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user.",
  "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-2026-76504"
  }, {
    "type" : "WEB",
    "url" : "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU"
  }, {
    "type" : "WEB",
    "url" : "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76504"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-177" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-30T13:17:20Z"
  }
}