CVE-2026-89420 Vulnerability Analysis & Exploit Details

CVE-2026-89420
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-89420 Details

Status: Received on 22 Sep 2026, 12:17 UTC

Published on: 22 Sep 2026, 12:17 UTC

CVSS Release:

CVE-2026-89420 Vulnerability Summary

CVE-2026-89420: 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.

Assessing the Risk of CVE-2026-89420

Access Complexity Graph

The exploitability of CVE-2026-89420 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-89420

No exploitability data is available for CVE-2026-89420.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-89420, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-89420, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-89420 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-89420 does not impact data integrity.
  • Availability: None
    CVE-2026-89420 does not affect system availability.

CVE-2026-89420 References

External References

CWE Common Weakness Enumeration

CWE-1284

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