CVE-2026-56709: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-6c2c-797q-5r9x
Share
CVSS 7.5
CWE-350
Published
Advisory Summary

CVE-2026-56709 is a HIGH (CVSS 7.5) security vulnerability vulnerability (CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product performs reverse dns resolution on an ip address to obtain the hostname and make a security decision, but it does not properly ensure that the ip address is truly associated with the hostname.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-56709 at a Glance

CVE Identifier CVE-2026-56709
GHSA Identifier GHSA-6c2c-797q-5r9x
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

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:N/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 None (I:N)
Availability None (A:N)

How to Fix CVE-2026-56709

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-2026-56709, 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-350: Reliance on Reverse DNS Resolution for a Security-Critical Action, where the product performs reverse dns resolution on an ip address to obtain the hostname and make a security decision, but it does not properly ensure that the ip address is truly associated with the hostname. 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

Grav before 3.9.2 fails to validate untrusted Host headers in the sendInvitationEmail() function when constructing token-bearing invitation links. Attackers can manipulate the Host header to poison invitation links and redirect users to attacker-controlled domains, bypassing the require_trusted_host protection which only covers password reset flows.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/getgrav/grav/security/advisories/GHSA-69vf-mjxw-x79j
NVD — CVE-2026-56709 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56709
www.vulncheck.com/advisories/grav-bef... WEB
https://www.vulncheck.com/advisories/grav-before-host-header-injection-via-sendinvitationemail

Frequently Asked Questions

What is CVE-2026-56709?
CVE-2026-56709 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-56709?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-56709?
CVE-2026-56709 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-56709?
CVE-2026-56709 is classified under CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action (The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.).
How can I check Maven dependencies for CVE-2026-56709?
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-6c2c-797q-5r9x",
  "modified" : "2026-08-25T03:32:09Z",
  "published" : "2026-08-25T03:32:09Z",
  "aliases" : [ "CVE-2026-56709" ],
  "details" : "Grav before 3.9.2 fails to validate untrusted Host headers in the sendInvitationEmail() function when constructing token-bearing invitation links. Attackers can manipulate the Host header to poison invitation links and redirect users to attacker-controlled domains, bypassing the require_trusted_host protection which only covers password reset flows.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/getgrav/grav/security/advisories/GHSA-69vf-mjxw-x79j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-56709"
  }, {
    "type" : "WEB",
    "url" : "https://www.vulncheck.com/advisories/grav-before-host-header-injection-via-sendinvitationemail"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-350" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-08-25T02:16:42Z"
  }
}