CVE-2026-55990: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-hpr4-88jh-4pvx
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CVSS 5.9
CWE-457
Published
Advisory Summary

CVE-2026-55990 is a MODERATE (CVSS 5.9) security vulnerability vulnerability (CWE-457: Use of Uninitialized Variable) affecting Software libraries in the Maven ecosystem. The weakness occurs when the code uses a variable that has not been initialized, leading to unpredictable or unintended results.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-55990 at a Glance

CVE Identifier CVE-2026-55990
GHSA Identifier GHSA-hpr4-88jh-4pvx
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-457: Use of Uninitialized Variable
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H).

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

How to Fix CVE-2026-55990

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-2026-55990, 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-457: Use of Uninitialized Variable, where the code uses a variable that has not been initialized, leading to unpredictable or unintended results. 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 NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when the 'dnscrypt:' clause lists more 'dnscrypt-provider-cert:' files than there are matching 'dnscrypt-secret-key:' files, Unbound fills only the matched prefix and leaves the tail slots at the '0xdb' fill that libsodium's allocator writes into every allocation. Unbound would then iterate over the number of cert files, not the actual slots, so it walks into a slot with garbage data filled with '0xdb' bytes. Any unauthenticated client that sends one UDP datagram of ≥ 68 bytes whose first 8 bytes are '0xdb' to 'dnscrypt-port' will use that garbage entry which leads to a garbage dereference killing the server. This is a silent faulty configuration that goes unnoticed until triggered with the right client query. Unbound needs to be compiled with DNSCrypt support ('--enable-dnscrypt').

References

NVD — CVE-2026-55990 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55990
www.nlnetlabs.nl/downloads/unbound/c... WEB
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-55990.txt

Frequently Asked Questions

What is CVE-2026-55990?
CVE-2026-55990 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-457: Use of Uninitialized Variable.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-55990?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-55990?
CVE-2026-55990 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-55990?
CVE-2026-55990 is classified under CWE-457: Use of Uninitialized Variable (The code uses a variable that has not been initialized, leading to unpredictable or unintended results.).
How can I check Maven dependencies for CVE-2026-55990?
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-hpr4-88jh-4pvx",
  "modified" : "2026-07-22T15:31:25Z",
  "published" : "2026-07-22T15:31:25Z",
  "aliases" : [ "CVE-2026-55990" ],
  "details" : "In NLnet Labs Unbound 1.7.0 up to and including 1.25.1, when the 'dnscrypt:' clause lists more 'dnscrypt-provider-cert:' files than there are matching 'dnscrypt-secret-key:' files, Unbound fills only the matched prefix and leaves the tail slots at the '0xdb' fill that libsodium's allocator writes into every allocation. Unbound would then iterate over the number of cert files, not the actual slots, so it walks into a slot with garbage data filled with '0xdb' bytes. Any unauthenticated client that sends one UDP datagram of ≥ 68 bytes whose first 8 bytes are '0xdb' to 'dnscrypt-port' will use that garbage entry which leads to a garbage dereference killing the server. This is a silent faulty configuration that goes unnoticed until triggered with the right client query. Unbound needs to be compiled with DNSCrypt support ('--enable-dnscrypt').",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-55990"
  }, {
    "type" : "WEB",
    "url" : "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-55990.txt"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-457" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-22T14:17:21Z"
  }
}