External risk intelligence

Adobe Connect CRLF Injection Vulnerability Allows Arbitrary Code Execution.

CVE advisorySeverity: CRITICAL (CVSS 10.0)

CVE-2026-121353

Adobe Connect is a web-based conferencing and collaboration platform designed to be accessible over the internet for remote meetings, webinars, and training sessions. Because it serves as a public-facing web application and communication gateway by design in normal deployment, the vulnerable surface is highly likely to be reachable from the internet.

Halo Surface Signal: 5 out of 5 — more likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

Adobe Connect is impacted by a vulnerability allowing for code execution within a user's session, potentially leading to unauthorized access or control. This issue does not require any action from the user to be exploited and affects the system's scope, meaning it could impact components beyond the initial target.

Code execution via malicious input.
High impact for user accounts and sessions.
Confirm relevance and exposure for Adobe Connect.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted data to Adobe Connect over the network. Because the vulnerability does not require user interaction and has a changed scope, a successful attack could allow an attacker to execute arbitrary code on the affected system, potentially leading to unauthorized access or control of a user's account or session.

Network access required.
CRLF injection trigger.
Arbitrary code execution risk.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in Adobe Connect could allow an attacker to execute arbitrary code on a user's system without interaction. When supported by the advisory, this could potentially lead to elevated access or control over a victim's account or session.

User account and session control.
Exploitation occurs over the network.
Potential for unauthorized system access.

Operational Fix

Recommended remediation, mitigation, and detection steps

To address this CRLF Injection vulnerability in Adobe Connect, the platform or application owner is likely responsible for remediation, supported by the infrastructure and security teams. The first crucial step is to identify all instances of Adobe Connect, determine their exposure and business criticality, and locate the accountable owner for each. Planning remediation efforts should then prioritize the most vulnerable and critical assets.

Identify platform owners and key stakeholders.
Verify external accessibility and criticality.
Plan phased remediation based on risk.

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 Adobe Connect and how is it used?

Adobe Connect is a web-based platform built for hosting remote meetings, interactive webinars, and collaborative training sessions. It acts as a digital communication gateway that allows organizations to stream presentations and manage shared content, typically accessed by participants via a web browser over the internet.

How does CVE-2026-121353 involve CRLF injection?

This vulnerability is classified as Improper Neutralization of CRLF Sequences. In plain terms, it means the application fails to properly clean data inputs, allowing an attacker to insert carriage return (CR) and line feed (LF) characters. These characters can manipulate how the server interprets incoming web traffic, leading to the execution of unintended, arbitrary code.

Does a user need to click a link to trigger this vulnerability?

No. Unlike many web vulnerabilities that rely on a victim clicking a malicious link, this issue does not require any user interaction. An attacker can initiate the exploit remotely by sending specifically formatted network traffic directly to the Adobe Connect system.

Why is Adobe Connect considered highly relevant here?

According to Halo Surface Signal, Adobe Connect is designed to be a public-facing web application for remote collaboration. Because the software is intended to be reachable from the internet by default, it is highly likely that your instance is exposed to network-based threats, making this vulnerability particularly significant for your perimeter.

How should I respond to this vulnerability?

Start by identifying every instance of Adobe Connect deployed across your environment and confirming who is responsible for each system. Once you have a complete inventory, assess the business criticality of these assets. Coordinate with your infrastructure and security teams to prioritize and plan a phased update or remediation strategy, focusing on your most critical and exposed systems first.

References

www.adobe.com/trust/security/products/connect/apsb26-191.html

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.