CVE-2026-48276: Adobe ColdFusion Critical File Upload RCE (CVSS 10.0)

Executive Summary

Adobe has disclosed CVE-2026-48276, a CVSS 10.0 Critical unrestricted file upload vulnerability in Adobe ColdFusion. The flaw (CWE-434) allows unauthenticated remote attackers to upload files of dangerous types, leading to arbitrary code execution without any user interaction. The vulnerability is part of Adobe's security bulletin APSB26-68, released June 30, 2026, which patches four critical ColdFusion flaws simultaneously.

All affected ColdFusion instances exposed to the internet should be patched immediately.

Vulnerability Overview

Affected Versions

Note: ColdFusion versions older than 2023 are end-of-life and will not receive patches. If you are running unsupported versions, upgrade immediately.

Technical Analysis

Root Cause

CVE-2026-48276 is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The vulnerability exists in ColdFusion's file upload handling logic, which fails to properly validate or restrict the type of files that can be submitted. An attacker can upload a file with a dangerous extension or content type (e.g., a .cfm web shell or executable) to an internet-facing ColdFusion instance.

Attack Chain

1. Attacker identifies internet-exposed Adobe ColdFusion instance
2. Crafts HTTP request with a malicious file upload (no authentication required)
3. ColdFusion processes the upload without validating file type
4. Attacker's file (web shell, payload) is written to a web-accessible path
5. Attacker requests the uploaded file, triggering server-side code execution
6. Full RCE achieved in the context of the ColdFusion process user
7. Post-exploitation: lateral movement, data exfiltration, ransomware deployment

Why CVSS 10.0?

The maximum CVSS score reflects the worst-case combination of factors:

• Network attack vector — exploitable remotely over the internet
• Low complexity — no special conditions or race conditions needed
• No privileges required — pre-authentication exploit
• No user interaction — fully automated exploitation is possible
• Changed scope — the vulnerability can affect resources beyond the vulnerable component
• High impact on Confidentiality, Integrity, and Availability

Impact

Successful exploitation provides attackers with:

• Arbitrary code execution on the ColdFusion server
• Full server compromise — read/write access to the file system
• Credential theft — ColdFusion datasource passwords, admin credentials
• Pivot point for lateral movement into internal networks
• Web shell persistence — attacker maintains ongoing access

Remediation

Immediate Actions

1. Apply Adobe's patch — Update ColdFusion 2025 to Update 10+, ColdFusion 2023 to Update 21+
2. Restrict external file upload endpoints — If update cannot be applied immediately, disable or restrict access to file upload functionality via WAF rules
3. Audit uploaded files — Review recently uploaded files for web shells or suspicious content
4. Check for compromise — Inspect ColdFusion logs for anomalous upload activity, especially from unknown IPs

If Immediate Patching Is Impossible

• Place ColdFusion behind a WAF or reverse proxy with upload filtering rules
• Restrict ColdFusion to internal networks only — remove from internet exposure
• Monitor file system for new .cfm, .cfc, or executable files in web-accessible directories
• Enable ColdFusion Lockdown Mode if not already applied

Lockdown Checklist

• Apply APSB26-68 patch
• Run Adobe's ColdFusion Security Analyzer post-patch
• Audit cfide/, CFIDE/, and custom application upload directories
• Review web server logs for POST requests to file upload endpoints from unexpected sources
• Rotate ColdFusion administrator and datasource credentials

Detection

Log Indicators

# Watch for unusual file uploads in ColdFusion logs
grep -i "upload" /path/to/coldfusion/logs/application.log
grep -iE "\.(cfm|cfc|exe|sh|jsp)" /path/to/coldfusion/logs/application.log

# Check for new files in web root (run after patch, then compare)
find /path/to/webroot -newer /path/to/reference_file -name "*.cfm"

Network Indicators

Context: APSB26-68 — Four Critical ColdFusion CVEs

This advisory is one of four critical CVEs patched simultaneously in Adobe's APSB26-68 bulletin:

The simultaneous disclosure of four CVSS 10.0 vulnerabilities in a single product is a rare and serious event. Organizations running ColdFusion should treat this bulletin as a critical security incident requiring emergency patch deployment.

Key Takeaways

1. CVSS 10.0 maximum score — no authentication, no user interaction, full RCE, changed scope
2. Unrestricted file upload allows web shell deployment as an initial access vector
3. Part of four simultaneous critical CVEs in Adobe ColdFusion (APSB26-68)
4. Patch immediately — ColdFusion 2025 → Update 10+, ColdFusion 2023 → Update 21+
5. If unpatched, remove from internet exposure and apply WAF controls immediately

References

• Adobe Security Bulletin APSB26-68
• NVD — CVE-2026-48276
• CWE-434: Unrestricted Upload of File with Dangerous Type
• CISA Known Exploited Vulnerabilities Catalog