Adobe ColdFusion CVE-2026-48276 (CVSS 10.0) RCE

Adobe has addressed CVE-2026-48276, a critical arbitrary code execution vulnerability in its ColdFusion web application development platform. This vulnerability, stemming from an unrestricted upload of files with dangerous types, has been assigned a maximum CVSS score of 10.0. This severity rating indicates a complete loss of confidentiality, integrity, and availability on affected systems.

The vulnerability affects Adobe ColdFusion 2023 and Adobe ColdFusion 2025, specifically versions prior to the latest security updates. Successful exploitation grants an unauthenticated attacker the ability to execute arbitrary code, leading to full control over the compromised server. The potential impact extends to any data and applications hosted or managed by the ColdFusion instance.

Adobe has released patches to remediate CVE-2026-48276 alongside other high-severity flaws. As of the latest advisory, there is no evidence of in-the-wild exploitation for this particular vulnerability or any of the issues addressed in the recent ColdFusion and Campaign Classic updates. Organizations utilizing affected ColdFusion instances should patch to mitigate immediate risks.

What is CVE-2026-48276 and why is it critical?

CVE-2026-48276 is an unrestricted file upload vulnerability in Adobe ColdFusion, rated with a CVSS score of 10.0, which can lead to arbitrary code execution. The vulnerability is critical because it offers a direct path to full system compromise without complex preconditions. Attackers can bypass standard security controls by uploading malicious files.

This vulnerability permits an attacker to upload files that should otherwise be restricted by type, such as executable scripts or web shells, to a ColdFusion server. Once uploaded, if the server is configured to execute content from the upload directory, the attacker can trigger the malicious code. The highest CVSS score of 10.0 reflects the complete compromise potential, including unauthorized access, data manipulation, and service disruption. Organizations running unpatched ColdFusion instances are therefore exposed to severe security risks. A similar high-severity vulnerability in an Adobe product, CVE-2025-54253 affecting Adobe AEM, also shows the severity of such RCE flaws.

What is the potential impact of CVE-2026-48276?

An attacker successfully exploiting CVE-2026-48276 can achieve arbitrary code execution, granting them extensive control over the compromised ColdFusion server. This level of access can have major effects on data, system integrity, and operational continuity.

The primary consequence is the complete compromise of the ColdFusion server. This means an attacker can install persistent backdoors, deploy malware, or use the server as a pivot point for further attacks within the internal network. Depending on the server's role, this could expose backend databases, connected services, and other internal resources.

Secondly, there is a significant risk of data theft and manipulation. ColdFusion applications often interact with sensitive customer data, proprietary business information, or intellectual property. An attacker with arbitrary code execution capabilities can access, exfiltrate, or tamper with this data, leading to severe confidentiality and integrity breaches. The impact on reputation and regulatory compliance can be substantial for affected entities.

Also, service disruption is a critical concern. Attackers can deface websites, render applications inoperable, or introduce malicious content, directly impacting business operations and user trust. The ability to execute arbitrary code provides the means to destabilize or entirely shut down services hosted on the vulnerable ColdFusion instance.

Organizations at risk include any entity deploying Adobe ColdFusion 2023 or Adobe ColdFusion 2025 in an unpatched state, particularly those with publicly accessible web applications. The broad applicability of ColdFusion across various industries means that a wide range of organizations, from government agencies to private enterprises, could be affected by this critical vulnerability.

Is CVE-2026-48276 being actively exploited?

As of the current reporting by Adobe, there is no evidence of in-the-wild exploitation for CVE-2026-48276 or any of the associated vulnerabilities addressed in the recent security updates for ColdFusion and Campaign Classic. Adobe explicitly stated that it has not found any exploits actively being used in attacks.

This absence of active exploitation provides a critical window for organizations to apply necessary patches before threat actors develop and deploy exploits. However, the high CVSS score of 10.0 and the straightforward nature of the arbitrary code execution via unrestricted file upload suggest that this vulnerability is highly attractive to attackers. Experience with similar critical vulnerabilities, such as the actively exploited RCE zero-day CVE-2025-20393 in Cisco products, shows that the time between public disclosure and active exploitation can be short.

How can CVE-2026-48276 be exploited?

Exploitation of CVE-2026-48276 uses an attacker's ability to upload a file with a dangerous type, such as a web shell or other executable script, to a vulnerable Adobe ColdFusion instance. The core mechanism is the ColdFusion server's inadequate validation of file types or content during an upload operation.

The attack typically proceeds as follows: an attacker identifies an endpoint within the ColdFusion application that accepts file uploads. By crafting a request that bypasses the application's intended file type restrictions, they can upload a malicious file (e.g., a .cfm file containing ColdFusion Markup Language code, or a .jsp file for underlying Java servers, designed to execute system commands). If the uploaded file is placed in a web-accessible directory and its dangerous type is not properly sanitized or restricted, it can then be accessed via a web browser.

Upon accessing the malicious file via a URL, the ColdFusion server interprets and executes its content. This execution then grants the attacker arbitrary code execution capabilities, allowing them to run operating system commands, manipulate server files, or establish a reverse shell for persistent control. The preconditions for this attack include network access to the vulnerable ColdFusion web server. While the research does not specify authentication requirements for CVE-2026-48276, such vulnerabilities often exist in publicly accessible upload functionalities or can be chained with other flaws to achieve unauthenticated access.

Which products and versions are affected by CVE-2026-48276?

CVE-2026-48276 specifically impacts installations of Adobe ColdFusion that have not applied the most recent security updates. Administrators must identify their ColdFusion version and update status to determine exposure.

The affected product lines and their vulnerable version ranges are detailed below:

  • Adobe ColdFusion 2023: All versions prior to Update 21 are vulnerable to CVE-2026-48276.
  • Adobe ColdFusion 2025: All versions prior to Update 10 are vulnerable to CVE-2026-48276.

The security updates released by Adobe, ColdFusion 2023 Update 21 and ColdFusion 2025 Update 10, contain the necessary fixes for this and several other critical vulnerabilities. Deployment should be immediate. Always back up systems before applying updates. Organizations should check their current ColdFusion build numbers against the official Adobe security bulletins to ensure their environments are patched.

What detection mechanisms are available for CVE-2026-48276?

Detection for CVE-2026-48276 primarily focuses on monitoring for suspicious file uploads, unusual process execution, and anomalous network activity originating from ColdFusion servers. A multi-layered approach using various security tools and logs is recommended to identify potential exploitation attempts or post-exploitation indicators.

  • Network Monitoring and Web Server Logs:
  • Monitor web server access logs for unusual HTTP POST requests to upload directories. Specifically, look for uploads of files with suspicious or unexpected extensions (e.g., .cfm, .jsp, .aspx, .php, .war, .exe) that are not typically permitted by legitimate application logic.
  • Analyze network traffic originating from the ColdFusion server for connections to unexpected external IP addresses or internal systems. This could indicate command-and-control (C2) communication or lateral movement post-exploitation.
  • Detect attempts to retrieve or execute recently uploaded files with unusual names or paths from web-accessible directories.
  • Endpoint Detection and Response (EDR) and System Logs:
  • Monitor ColdFusion server logs (e.g., cfserver.log, exception.log, application.log) for errors related to file uploads or unexpected script execution. Look for entries indicating failed or successful file operations on unusual paths.
  • Implement EDR rules to detect new process creation from the main ColdFusion process (java.exe or coldfusion.exe) that deviate from normal operations. This includes attempts to execute system utilities (e.g., cmd.exe, powershell.exe, bash), create new users, modify system files, or establish reverse shells.
  • Alert on the creation or modification of files in web-accessible directories with unusual content, suspicious permissions, or known web shell signatures.
  • Look for modifications to critical ColdFusion configuration files or unexpected changes within the web root directories.
  • Web Application Firewalls (WAFs):
  • Configure WAF rules to detect and block file uploads that attempt to bypass file extension restrictions. This includes checking for double extensions (e.g., file.jpg.cfm), null byte injection, or other obfuscation techniques.
  • Deploy WAF signatures that inspect the content of uploaded files for known web shell patterns, malicious ColdFusion Markup Language (CFML) functions, or other suspicious code snippets.
  • Monitor WAF logs for attempts to probe for file upload vulnerabilities or exploit known ColdFusion attack vectors.
  • File Integrity Monitoring (FIM):
  • Deploy FIM solutions to continuously monitor critical ColdFusion directories, including the web root, application directories, and configuration files, for unauthorized modifications, creations, or deletions. Alerts from FIM can indicate a successful compromise or post-exploitation activity.

How can CVE-2026-48276 be remediated and mitigated?

The primary and most effective remediation for CVE-2026-48276 is to apply the latest security updates provided by Adobe for ColdFusion. These patches directly address the underlying vulnerability and are essential for securing affected systems.

  • Patching:
  • Organizations running Adobe ColdFusion 2023 must update their installations to Update 21 or a later version.
  • Organizations running Adobe ColdFusion 2025 must update their installations to Update 10 or a later version.
  • These updates include fixes for CVE-2026-48276 and other critical and important vulnerabilities. Deployment should be immediate.
  • Always back up systems before applying updates.
  • Workarounds and Mitigations (if immediate patching is not feasible):
  • Strict File Upload Validation: Implement rigorous validation of all uploaded files. This includes whitelisting allowed file types and extensions, never relying solely on client-side validation. Enforce validation of file headers, magic bytes, and content to ensure files conform to expected types.
  • Isolate Upload Directories: Configure the web server or ColdFusion application to store all uploaded files in a dedicated, non-executable directory that is outside the web root. Files should only be served or processed after thorough validation by a controlled application component.
  • Least Privilege Principle: Ensure that the ColdFusion service runs with the absolute minimum necessary operating system privileges. This restricts the potential damage an attacker can inflict if arbitrary code execution is achieved.
  • Network Segmentation: Implement strong network segmentation to isolate ColdFusion servers from other critical internal systems. This limits the scope of potential lateral movement in the event of a successful exploitation.
  • Web Application Firewall (WAF): Deploy and configure a WAF to actively block malicious file upload attempts. WAF rules can be tailored to identify and prevent uploads of suspicious file types or content that indicate web shell deployment.
  • Input Validation: Strengthen input validation across all application inputs, not just file uploads. This helps prevent other forms of injection attacks and ensures that ColdFusion processes only expected and safe data.
  • Disable Unused Features: Disable any ColdFusion features, services, or connectors that are not actively required for application functionality. Reducing the attack surface minimizes potential entry points.
  • Continuous Monitoring:
  • Even after applying patches, maintain continuous monitoring of ColdFusion servers for any indicators of compromise.
  • This includes regular review of application, web server, and operating system logs for unusual activity, unexpected process executions, or anomalous network connections.
  • Regularly perform security audits and penetration tests on ColdFusion environments to proactively identify and address potential weaknesses before they can be exploited.

Technical Takeaways

  • CVE-2026-48276 is a critical arbitrary code execution vulnerability in Adobe ColdFusion, assigned a maximum CVSS score of 10.0.
  • The flaw is categorized as an unrestricted upload of files with dangerous types, enabling attackers to execute arbitrary code on vulnerable servers.
  • Affected versions include Adobe ColdFusion 2023 prior to Update 21 and Adobe ColdFusion 2025 prior to Update 10.
  • Adobe has released security updates to remediate this vulnerability, and no in-the-wild exploitation has been reported as of the disclosure date.
  • Effective remediation requires the immediate application of the latest security patches, complemented by strong input validation, strict file upload restrictions, and continuous monitoring for suspicious activities.