Terminal escape injection in Hex output
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Partial Red Hat: 30 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
Hex from 0.0.1 before 2.5.2 prints package metadata and repository strings to the terminal without neutralizing control characters, which is CWE-150. A malicious package publisher or hostile repository server can embed terminal escape sequences or Unicode bidirectional overrides in these fields, which can forge displayed URLs and commands, conceal real output or write to the clipboard. No authentication is required, only the ability to publish a package.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| hexpm | hex | 0.0.1 to before 2.5.2 | 2.5.2 | Patch available | CNA |
- hex Vendorhexpm Affected 0.0.1 to before 2.5.2 Fixed in 2.5.2 Patch available CNA
CPE names CNA · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:* | — | — | — |
- cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:* Versions — — ·—
Remediation
Upgrade hex to version 2.5.2, which contains the fix. Red Hat lists no available fix plan for Ansible Automation Orchestrator 2026, Confidential Cluster Operator, Confidential Compute Attestation, Lightspeed Services for Advanced Cluster Management, Logging Subsystem for Red Hat OpenShift and other products.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
- Fix · CNA hex (hexpm) Fixed in 2.5.2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
hexpm hex 2.5.2
7 records Highest priority Priority LOW 7 LOW
Other records, highest priority first
- TI-2026-71017 Path traversal in Hex via unvalidated dependency app namesPriority LOW 35
- TI-2026-71021 Hex release-age cooldown is lifted when a locked release is retiredPriority LOW 33
- TI-2026-71020 Hex mix hex.package fetch writes unverified tarballs to stdoutPriority LOW 30
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Ansible Automation Orchestrator 2026 | Affected | No fix yet: Fix deferred |
| Confidential Cluster Operator | Affected | No fix yet: Fix deferred |
| Confidential Compute Attestation | Affected | No fix yet: Fix deferred |
| Lightspeed Services for Advanced Cluster Management | Affected | No fix yet: Fix deferred |
| Logging Subsystem for Red Hat OpenShift | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| Pen Drive Powered by Red Hat Lightspeed | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform Ansible Core 2 | Affected | No fix yet: Fix deferred |
| Red Hat Developer Hub 1 | Affected | No fix yet: Fix deferred |
| Red Hat Discovery 2 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux command line assistant | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Affected | No fix yet: Fix deferred |
| Red Hat Lightspeed Services for OCP | Affected | No fix yet: Fix deferred |
| Red Hat Offline Knowledge Portal | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Update Service | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 16.2 | Affected | No fix yet: Fix deferred |
| Red Hat OpenStack Platform 17.1 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Artifact Signer | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Profile Analyzer | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-12 Threatist record created from CVE-2026-81856
- 2026-10-13 Affected versions changed · Red Hat
- 2026-10-13 CVSS score added · Red Hat
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-27 Affected versions changed · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
More hexpm vulnerabilities
- TI-2026-24685 Lockfile checksums not verified in Hex allows dependency integrity bypass CVSS 4.0HIGH 8.9
- TI-2026-52887 OAuth token exchange grants repository scopes for organizations the principal cannot access CVSS 4.0HIGH 8.3
- TI-2026-17414 Password Reset Tokens Do Not Expire CVSS 4.0CRITICAL 9.5
- TI-2026-59264 Refresh tokens accepted as private repository credentials at the CDN CVSS 4.0LOW 2.3
- TI-2026-52890 Explicit organization scopes survive token refresh after membership ends CVSS 4.0LOW 2.3
- TI-2026-17410 Cross-site scripting (XSS) in OAuth Device Authorization screen CVSS 4.0HIGH 8.5
Sources
- CVE-2026-81856 · CVE Program
- CVE-2026-81856 · NVD
- FIRST EPSS
- CVE-2026-81856 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences