CVE-2026-89420: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-96m7-5wfv-978m
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CWE-1284
Published
Advisory Summary

CVE-2026-89420 is a HIGH security vulnerability vulnerability (CWE-1284: Improper Validation of Specified Quantity in Input) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-89420 at a Glance

CVE Identifier CVE-2026-89420
GHSA Identifier GHSA-96m7-5wfv-978m
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-1284: Improper Validation of Specified Quantity in Input
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-89420

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-2026-89420, 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-1284: Improper Validation of Specified Quantity in Input, where the product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties. 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

Improper Validation of Specified Quantity in Input in ZenHive mpp allows a client holding an open payment channel to obtain paid resources without being charged. MPP.Session.Actions.accept_voucher/3 in lib/mpp/session/actions.ex treats a voucher whose cumulativeAmount equals the channel's already-accepted cumulative amount as an idempotent success, returning the channel unchanged without calling maybe_spend/2. The credential verifies, the protected resource is served, and spent and units stay where they were. Because the server issues a fresh challenge per request and the credential replay store keys on challenge id and payload, the same signed voucher can be re-presented under every new challenge, so one paid voucher yields an unbounded number of paid units. The path is reachable from any method built on MPP.Session.Method through the Plug, MCP, JSON-RPC and WebSocket transports. This issue affects mpp: from 0.14.0 before 0.16.2.

References

GitHub Advisory / Wiki ADVISORY
https://github.com/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf
NVD — CVE-2026-89420 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89420
Security Fix Commit FIX COMMIT
https://github.com/ZenHive/mpp/commit/7270edc1dcfb58250cc5ee812876609206564165
Security Fix Commit FIX COMMIT
https://github.com/ZenHive/mpp/commit/82df569c898be1137189e3648e1edb4af6363651
cna.erlef.org/cves/cve-2026-89420... WEB
https://cna.erlef.org/cves/CVE-2026-89420.html
osv.dev/vulnerability/eef-c... WEB
https://osv.dev/vulnerability/EEF-CVE-2026-89420

Frequently Asked Questions

What is CVE-2026-89420?
CVE-2026-89420 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-1284: Improper Validation of Specified Quantity in Input.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-89420?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-89420?
CVE-2026-89420 is classified under CWE-1284: Improper Validation of Specified Quantity in Input (The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.).
How can I check Maven dependencies for CVE-2026-89420?
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-96m7-5wfv-978m",
  "modified" : "2026-09-22T12:30:26Z",
  "published" : "2026-09-22T12:30:26Z",
  "aliases" : [ "CVE-2026-89420" ],
  "details" : "Improper Validation of Specified Quantity in Input in ZenHive mpp allows a client holding an open payment channel to obtain paid resources without being charged.\n\nMPP.Session.Actions.accept_voucher/3 in lib/mpp/session/actions.ex treats a voucher whose cumulativeAmount equals the channel's already-accepted cumulative amount as an idempotent success, returning the channel unchanged without calling maybe_spend/2. The credential verifies, the protected resource is served, and spent and units stay where they were. Because the server issues a fresh challenge per request and the credential replay store keys on challenge id and payload, the same signed voucher can be re-presented under every new challenge, so one paid voucher yields an unbounded number of paid units. The path is reachable from any method built on MPP.Session.Method through the Plug, MCP, JSON-RPC and WebSocket transports.\n\nThis issue affects mpp: from 0.14.0 before 0.16.2.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/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/ZenHive/mpp/security/advisories/GHSA-8c63-r789-xrrf"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-89420"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ZenHive/mpp/commit/7270edc1dcfb58250cc5ee812876609206564165"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ZenHive/mpp/commit/82df569c898be1137189e3648e1edb4af6363651"
  }, {
    "type" : "WEB",
    "url" : "https://cna.erlef.org/cves/CVE-2026-89420.html"
  }, {
    "type" : "WEB",
    "url" : "https://osv.dev/vulnerability/EEF-CVE-2026-89420"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1284" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-22T12:17:14Z"
  }
}