CVE-2026-81856 Vulnerability Analysis & Exploit Details

CVE-2026-81856
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-2026-81856 Details

Status: Received on 12 Oct 2026, 16:17 UTC

Published on: 12 Oct 2026, 16:17 UTC

CVSS Release:

CVE-2026-81856 Vulnerability Summary

CVE-2026-81856: Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks. Hex prints strings supplied by the package repository and the documentation search service straight to the terminal through Hex.Shell.info/1 and Hex.Shell.error/1, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in mix hex.info, search results in mix hex.package search and mix hex.search, owner and organization listings, publish and sponsor URLs, the authenticated username in mix hex.user, policy identities in mix hex.policy, and API error bodies rendered by Hex.Utils.print_error_result/1. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package. This issue affects hex: from 0.0.1 before 2.5.2.

Assessing the Risk of CVE-2026-81856

Access Complexity Graph

The exploitability of CVE-2026-81856 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-2026-81856

No exploitability data is available for CVE-2026-81856.

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-2026-81856, 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-2026-81856, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-81856 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-81856 does not impact data integrity.
  • Availability: None
    CVE-2026-81856 does not affect system availability.

CVE-2026-81856 References

External References

CWE Common Weakness Enumeration

CWE-150

CAPEC Common Attack Pattern Enumeration and Classification

  • Email Injection CAPEC-134 An adversary manipulates the headers and content of an email message by injecting data via the use of delimiter characters native to the protocol.
  • Using Meta-characters in E-mail Headers to Inject Malicious Payloads CAPEC-41 This type of attack involves an attacker leveraging meta-characters in email headers to inject improper behavior into email programs. Email software has become increasingly sophisticated and feature-rich. In addition, email applications are ubiquitous and connected directly to the Web making them ideal targets to launch and propagate attacks. As the user demand for new functionality in email applications grows, they become more like browsers with complex rendering and plug in routines. As more email functionality is included and abstracted from the user, this creates opportunities for attackers. Virtually all email applications do not list email header information by default, however the email header contains valuable attacker vectors for the attacker to exploit particularly if the behavior of the email client application is known. Meta-characters are hidden from the user, but can contain scripts, enumerations, probes, and other attacks against the user's system.
  • Web Server Logs Tampering CAPEC-81 Web Logs Tampering attacks involve an attacker injecting, deleting or otherwise tampering with the contents of web logs typically for the purposes of masking other malicious behavior. Additionally, writing malicious data to log files may target jobs, filters, reports, and other agents that process the logs in an asynchronous attack pattern. This pattern of attack is similar to "Log Injection-Tampering-Forging" except that in this case, the attack is targeting the logs of the web server and not the application.
  • Log Injection-Tampering-Forging CAPEC-93 This attack targets the log files of the target host. The attacker injects, manipulates or forges malicious log entries in the log file, allowing them to mislead a log audit, cover traces of attack, or perform other malicious actions. The target host is not properly controlling log access. As a result tainted data is resulting in the log files leading to a failure in accountability, non-repudiation and incident forensics capability.

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