CVE-2026-20249: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-q3fg-q5c4-7677
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CVSS 8.6
CWE-704
Published
Advisory Summary

CVE-2026-20249 is a HIGH (CVSS 8.6) security vulnerability vulnerability (CWE-704: Incorrect Type Conversion or Cast) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not correctly convert an object, resource, or structure from one type to a different type.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-20249 at a Glance

CVE Identifier CVE-2026-20249
GHSA Identifier GHSA-q3fg-q5c4-7677
Severity HIGH
CVSS v3.1 Base Score 8.6
CWE Classification CWE-704: Incorrect Type Conversion or Cast
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.6

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:C/C:N/I:N/A:H).

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

How to Fix CVE-2026-20249

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-2026-20249, 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-704: Incorrect Type Conversion or Cast, where the product does not correctly convert an object, resource, or structure from one type to a different type. 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 certification authentication feature of Internet Key Exchange version 2 (IKEv2) for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly. This vulnerability is due to a logic error during the certificate authentication phase of the IKEv2 connection setup. An attacker could exploit this vulnerability by attempting to establish an IKEv2 VPN connection with a crafted certificate. A successful exploit could allow the attacker to cause the IKEv2 process to crash, causing a denial of service (DoS) condition.

References

NVD — CVE-2026-20249 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20249
Software Security Information SECURITY
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2cert-dos-uWyc2xtv

Frequently Asked Questions

What is CVE-2026-20249?
CVE-2026-20249 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-704: Incorrect Type Conversion or Cast.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-20249?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-20249?
CVE-2026-20249 has a CVSS v3.1 base score of 8.6 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.
What CWE is associated with CVE-2026-20249?
CVE-2026-20249 is classified under CWE-704: Incorrect Type Conversion or Cast (The product does not correctly convert an object, resource, or structure from one type to a different type.).
How can I check Maven dependencies for CVE-2026-20249?
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-q3fg-q5c4-7677",
  "modified" : "2026-09-16T21:32:49Z",
  "published" : "2026-09-16T21:32:49Z",
  "aliases" : [ "CVE-2026-20249" ],
  "details" : "A vulnerability in the certification authentication feature of Internet Key Exchange version 2 (IKEv2) for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly.\n\nThis vulnerability is due to a logic error during the certificate authentication phase of the IKEv2 connection setup. An attacker could exploit this vulnerability by attempting to establish an IKEv2 VPN connection with a crafted certificate. A successful exploit could allow the attacker to cause the IKEv2 process to crash, causing a denial of service (DoS) condition.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-20249"
  }, {
    "type" : "WEB",
    "url" : "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2cert-dos-uWyc2xtv"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-704" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-16T21:17:08Z"
  }
}