Skip to content
OpenAdvisories
Low · 2.3 CVE-2026-81856 EUVD-2026-97512

Terminal escape sequence injection in Hex via unneutralized server-supplied output

Published Oct 12, 2026 · Updated Nov 11, 2026 · Assigned by EEF

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.

Affected products

VendorProductAffectedFixed
hexpm hex 0.0.1 – < 2.5.2 2.5.2

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 erlang-hex 2.5.3-2 —
Debian 13 erlang-hex No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 erlang-hex No fix yet —
Ubuntu 26.04 LTS erlang-hex No fix yet —
Ubuntu 24.04 LTS erlang-hex No fix yet —

References