CVE-2026-56812 Vulnerability Analysis & Exploit Details

CVE-2026-56812
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-2026-56812 Details

Status: Received on 07 Jul 2026, 16:16 UTC

Published on: 07 Jul 2026, 16:16 UTC

CVSS Release:

CVE-2026-56812 Vulnerability Summary

CVE-2026-56812: Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix (Presence JavaScript client) allows an attacker with ordinary channel access to cause a persistent client-side denial of service against every viewer of a presence channel topic. This vulnerability is associated with program files assets/js/phoenix/presence.js and program routines Presence.syncState and Presence.syncDiff. The Phoenix JavaScript presence client checks whether a presence already exists with a bare truthiness test (state[key]) instead of an own-property check. Presence keys can be attacker-controlled, because applications track presences under a username or id supplied by the client. A user who joins a channel choosing a key that is an Object.prototype member name (__proto__, constructor, toString, hasOwnProperty, and similar) makes that lookup return JavaScript's built-in Object.prototype instead of undefined. Because the prototype is truthy, the code treats it as an existing presence and reads .metas.map(...) off it, which throws an uncaught TypeError. The exception propagates out of the presence message handler, so the local state is never updated and onSync() never fires. Because the malicious key is tracked on the server, it is re-pushed on every presence update and keeps re-throwing, so presence sync stays broken for every viewer of that channel topic until the attacker leaves. Both syncState and syncDiff use the same unsafe existence-check pattern. The impact is limited to the affected topic and is a read-time confusion of the prototype object, not a mutation of Object.prototype (it is not prototype pollution). This issue affects phoenix: from 1.2.0-rc.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9.

Assessing the Risk of CVE-2026-56812

Access Complexity Graph

The exploitability of CVE-2026-56812 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-2026-56812

No exploitability data is available for CVE-2026-56812.

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-2026-56812, 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-2026-56812, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-56812 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-56812 does not impact data integrity.
  • Availability: None
    CVE-2026-56812 does not affect system availability.

CVE-2026-56812 References

External References

CWE Common Weakness Enumeration

CWE-754

Protect Your Infrastructure against CVE-2026-56812: Combat Critical CVE Threats

Stay updated with real-time CVE vulnerabilities and take action to secure your systems. Enhance your cybersecurity posture with the latest threat intelligence and mitigation techniques. Develop the skills necessary to defend against CVEs and secure critical infrastructures. Join the top cybersecurity professionals safeguarding today's infrastructures.

Other 5 Recently Published CVEs Vulnerabilities

  • CVE-2026-57851 – MSI Feature Manager contains a local privilege escalation vulnerability in the KernCoreLib64.sys kernel driver that allows any locally logged-on us...
  • CVE-2026-23698 – Vtiger CRM through 8.4.0 contains an authenticated remote code execution vulnerability in the admin module import feature that allows administrator...
  • CVE-2026-23697 – Vtiger CRM before 8.4.0 contains an authenticated file upload vulnerability that allows low-privileged users to achieve remote code execution by up...
  • CVE-2026-14904 – AWS Research and Engineering Studio (RES) is an open-source solution that enables researchers and engineers to create and manage secure virtual des...
  • CVE-2026-13020 – A Weak Password Recovery Mechanism for Forgotten Password exists in Esri Portal for ArcGIS versions 12.1 and earlier on Windows, Linux and Kubernet...