CVE-2026-81856

2.3Low

Published 12 Oct 2026 · NVD status: Deferred · AI triage by gemini-3.8-flash

2.3Low

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Passive
Impact: Limited impact
Weakness: CWE-150

Impact

A malicious package publisher can manipulate terminal output, spoof displayed commands, conceal text, or modify your clipboard via OSC 52. They only need to publish a package with crafted metadata that a developer views using Mix hex commands.

Root cause

Hex outputs remote package metadata, URLs, and API error messages directly to the terminal without stripping ANSI escape codes or Unicode control sequences.

Affected systems

hex from 0.0.1 before 2.5.2

CVSS v4.0 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/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

Fix & remediation

Upgrade Hex to version 2.5.2 or later. If upgrading immediately is not possible, avoid running terminal-rendering commands like 'mix hex.info' or 'mix hex.search' on untrusted packages.

shell

$ mix local.hex --force

AI-suggested. Run it in staging first and check it against the vendor advisory. Why?

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NVD description

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.

References

Source: nvd.nist.gov/vuln/detail/CVE-2026-81856