External risk intelligence

openssl_encrypt Terminal Control Character Injection Vulnerability.

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-81696

The vulnerability involves terminal control character injection during the execution of an 'info' command on local files. This is a client-side interaction typically performed by a user in a local terminal environment rather than an internet-facing network service or web application.

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability affects the `openssl_encrypt` tool, allowing attackers to inject malicious characters into file metadata displayed by the `info` command. This could potentially mislead users by altering the verification information they see. The primary concern is to confirm if this specific tool and command are in use within your environment.

Malicious metadata can fake command output.
Misleading output could impact user trust.
Confirm tool usage and command execution.

Attack Path

How an attacker could exploit the issue

An attacker could target users by crafting a malicious file containing special characters. When a user runs the `info` command on this file using a vulnerable version of `openssl_encrypt`, these characters could manipulate the terminal's output, falsely displaying verified information and misleading the user.

Malicious file entry required.
`info` command triggers terminal escape sequences.
Leads to forged verification information display.

Live Threat

Current exploitation, exposure, and threat context

When the `info` command is used with crafted files, terminal control characters could alter the displayed verification information. This vulnerability impacts local users interacting with the `openssl_encrypt` tool.

Forged verification information could be displayed.
Malicious files could trigger the display.
Users may be misled by forged data.

Operational Fix

Recommended remediation, mitigation, and detection steps

The `openssl_encrypt` `info` command's failure to sanitize terminal control characters in file metadata means that application owners and platform teams are likely responsible for identifying and managing this vulnerability. The first practical step is to locate instances of `openssl_encrypt` in use, determine if they are exposed to users who might execute the `info` command with crafted files, and then prioritize remediation based on that exposure.

Application owners should manage the issue.
Verify `openssl_encrypt` `info` command usage.
Plan remediation for affected systems.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is openssl_encrypt?

openssl_encrypt is a software utility used for data processing and file management tasks. Developers and system administrators often use it to handle encryption-related workflows and verify file metadata. It is a standalone tool distinct from the core OpenSSL libraries, specifically designed to help users inspect and manage files through various command-line operations.

What does CVE-2026-81696 mean by terminal injection?

This vulnerability is classified as CWE-117, or Improper Output Neutralization for Logs. It occurs when a program fails to strip away hidden codes that control terminal behavior. By embedding these codes in file metadata, an attacker can trick your terminal into overwriting or repainting its own display, effectively hiding the truth or showing fake verification data when you run the info command.

How does an attacker trigger this vulnerability?

An attacker must provide you with a specially crafted file containing malicious terminal control characters. The issue is only triggered when you actively run the info command on that specific file. Simply storing, downloading, or having the file on your system does not execute the attack; the terminal must process the file's metadata while the command is running.

Do I need to worry about this if I use openssl_encrypt?

Halo Surface Signal notes this is very unlikely to be an internet-facing threat. Because the vulnerability requires a user to manually run the info command on a malicious file in a local terminal, it is a client-side risk. If your use of the tool is automated and does not display metadata to users, or if you do not interact with untrusted files, your risk is significantly lower.

What is the first step to address CVE-2026-81696?

Start by auditing your systems to identify where openssl_encrypt versions older than 1.4.9 are installed. Once located, restrict or monitor the use of the info command, especially when handling files from external or untrusted sources. The goal is to prevent users from executing this command on files that have not been vetted, while you plan to update to version 1.4.9 or later.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.