CVE-2026-7839: Software Security Vulnerability Vulnerability

CRITICAL
Advisory Identifier: GHSA-h7cc-6wq3-9h7x
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CVSS 9.1
CWE-798
Published
Advisory Summary

CVE-2026-7839 is a CRITICAL (CVSS 9.1) security vulnerability vulnerability (CWE-798: Use of Hard-coded Credentials) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product contains hard-coded credentials, such as a password or cryptographic key.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-7839 at a Glance

CVE Identifier CVE-2026-7839
GHSA Identifier GHSA-h7cc-6wq3-9h7x
Severity CRITICAL
CVSS v3.1 Base Score 9.1
CWE Classification CWE-798: Use of Hard-coded Credentials
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-2026-7839

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-2026-7839, 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-798: Use of Hard-coded Credentials, where the product contains hard-coded credentials, such as a password or cryptographic key. 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

UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string "adminadmi2" as the admin password via strcpy_s(saved_password, 64, "adminadmi2"). The HTTP Basic-auth handler wi_decode_auth() checks this password without rate-limiting or lockout. Any remote attacker who can reach the repeater HTTP port (default TCP 80) can authenticate as administrator using the well-known default credential on a fresh or unmodified installation, gaining full control of the repeater configuration including allow/deny rules and session visibility.

References

NVD — CVE-2026-7839 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-7839
Software Source Repository REPOSITORY
https://github.com/ultravnc/UltraVNC
uvnc.com WEB
https://uvnc.com
www.securin.io/zero-days/cve-2026-... WEB
https://www.securin.io/zero-days/cve-2026-7839-hardcoded-default-admin-password-adminadmi2-ultravnc-repeater

Frequently Asked Questions

What is CVE-2026-7839?
CVE-2026-7839 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-798: Use of Hard-coded Credentials.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-7839?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-7839?
CVE-2026-7839 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-2026-7839?
CVE-2026-7839 is classified under CWE-798: Use of Hard-coded Credentials (The product contains hard-coded credentials, such as a password or cryptographic key.).
How can I check Maven dependencies for CVE-2026-7839?
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-h7cc-6wq3-9h7x",
  "modified" : "2026-07-09T06:31:59Z",
  "published" : "2026-07-01T06:31:34Z",
  "aliases" : [ "CVE-2026-7839" ],
  "details" : "UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string \"adminadmi2\" as the admin password via strcpy_s(saved_password, 64, \"adminadmi2\"). The HTTP Basic-auth handler wi_decode_auth() checks this password without rate-limiting or lockout. Any remote attacker who can reach the repeater HTTP port (default TCP 80) can authenticate as administrator using the well-known default credential on a fresh or unmodified installation, gaining full control of the repeater configuration including allow/deny rules and session visibility.",
  "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-2026-7839"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ultravnc/UltraVNC"
  }, {
    "type" : "WEB",
    "url" : "https://uvnc.com"
  }, {
    "type" : "WEB",
    "url" : "https://www.securin.io/zero-days/cve-2026-7839-hardcoded-default-admin-password-adminadmi2-ultravnc-repeater"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-798" ],
    "severity" : "CRITICAL",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-01T05:16:24Z"
  }
}