Introduction
Adobe's April 2026 Patch Tuesday brought a Priority 1 security update for ColdFusion, and the headliner is CVE-2026-27304: a critical Improper Input Validation flaw that enables arbitrary code execution without any user interaction. Given ColdFusion's documented history as a target for initial access into government and enterprise networks, this is a vulnerability that defenders managing ColdFusion infrastructure need to address immediately.
Adobe ColdFusion is a commercial rapid web application development platform used to build and deploy dynamic websites and web applications. While it represents roughly 0.2% of all websites whose server side programming language is known, according to W3Techs, that still translates to thousands of enterprise deployments globally, many of which sit in sensitive environments. Its presence in government and financial sector infrastructure makes any critical ColdFusion vulnerability worth paying attention to.
Technical Information
Root Cause
CVE-2026-27304 is classified under CWE-20 (Improper Input Validation). The core issue is insufficient validation of user supplied input within the ColdFusion application server. Because ColdFusion is a closed source product, no public source code diff is available, but the patch touches three ColdFusion packages: adminapi, administrator, and CCS. This suggests the input validation remediation is located within the administrative and core configuration services layer of the product.
CVSS Scoring and Attack Vector
The vulnerability carries a CVSS 3.1 base score of 9.3 with the following vector string:
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
Breaking this down:
| Metric | Value | Meaning |
|---|---|---|
| Attack Vector (AV) | Adjacent (A) | Attacker must be on the same or an adjacent network segment |
| Attack Complexity (AC) | Low (L) | No special conditions or preparation required |
| Privileges Required (PR) | None (N) | No authentication needed |
| User Interaction (UI) | None (N) | No victim action required |
| Scope (S) | Changed (C) | Impact extends beyond the vulnerable component |
| Confidentiality (C) | High (H) | Complete loss of confidentiality |
| Integrity (I) | High (H) | Complete loss of integrity |
| Availability (A) | None (N) | No impact on availability |
The Adjacent Network attack vector is a noteworthy detail. It indicates that exploitation requires the attacker to be on the same network segment or an adjacent one, rather than being fully remotely exploitable over the open internet. This does not diminish the severity for organizations where ColdFusion servers are accessible from internal network segments, VPNs, or shared hosting environments.
Attack Flow
Based on the available technical details, the exploitation path works as follows:
- An attacker with network adjacency to the target ColdFusion server crafts a malicious request designed to bypass the server's input validation mechanisms.
- The crafted request is sent to the ColdFusion server. No authentication or user interaction is required.
- Due to insufficient validation, the attacker gains the ability to modify variables and gain unauthorized access.
- This leads to arbitrary code execution in the context of the current user running the ColdFusion process.
- Because the scope is "Changed," the impact can extend beyond the ColdFusion application itself, potentially affecting the underlying operating system or other components.
Companion Vulnerabilities in APSB26-38
CVE-2026-27304 is the highest scoring vulnerability in security bulletin APSB26-38, but it is not the only one. Applying the cumulative update mitigates several critical attack vectors simultaneously:
| CVE Number | Vulnerability Category | Impact | CVSS Score |
|---|---|---|---|
| CVE-2026-27304 | Improper Input Validation (CWE-20) | Arbitrary code execution | 9.3 |
| CVE-2026-27305 | Path Traversal (CWE-22) | Arbitrary file system read | 8.6 |
| CVE-2026-27306 | Improper Input Validation (CWE-20) | Arbitrary code execution | 8.4 |
| CVE-2026-34619 | Path Traversal (CWE-22) | Security feature bypass | 7.7 |
| CVE-2026-27282 | Improper Input Validation (CWE-20) | Security feature bypass | 7.5 |
| CVE-2026-27307 | Uncontrolled Resource Consumption (CWE-400) | Application denial of service | 2.4 |
| CVE-2026-27308 | Uncontrolled Resource Consumption (CWE-400) | Application denial of service | 2.4 |
Patch Information
Adobe released the official patch for CVE-2026-27304 on April 14, 2026, through security bulletin APSB26-38. The fix is delivered entirely through Adobe's cumulative hotfix JAR mechanism.
Patched Versions
| Product | Patched Version | Build Number | Hotfix JAR |
|---|---|---|---|
| ColdFusion 2025 | Update 7 | 2025,0,07,331586 | hotfix-007-331586.jar |
| ColdFusion 2023 | Update 19 | 2023,0,19,330899 | hotfix-019-330899.jar |
Both updates are cumulative, meaning they bundle every previous fix. Administrators who have fallen behind on patching can jump directly to these versions without installing interim updates first.
Beyond the input validation fix for CVE-2026-27304, these updates also refresh the underlying servlet container: ColdFusion 2025 Update 7 upgrades its bundled Tomcat to 10.1.53.0, while ColdFusion 2023 Update 19 moves to Tomcat 9.0.116.0.
Installation
Administrators can apply the patch through the Package Manager inside the ColdFusion Administrator UI by navigating to Package Manager > Packages > Check for Updates > Update. Alternatively, an offline manual installation can be performed by downloading the hotfix JAR and running it with the ColdFusion bundled JRE:
# ColdFusion 2025 (Windows example) <cf_root>\jre\bin\java.exe -jar hotfix-007-331586.jar # ColdFusion 2023 (Linux example) <cf_root>/jre/bin/java -jar hotfix-019-330899.jar
A ColdFusion restart is required after installation. Post install, the build number displayed in the Administrator should match the values listed in the table above, providing a quick way to confirm the patch has taken effect.
Additional Hardening
Adobe recommends several configuration changes alongside patching:
- Update the ColdFusion JDK or JRE LTS version to the latest update release.
- On JEE installations, set the following JVM flag in the startup file:
-Djdk.serialFilter=!org.mozilla.**;!com.sun.syndication.**;!org.apache.commons.beanutils.**;!org.jgroups.**;!com.sun.rowset.**;!com.mysql.cj.jdbc.interceptors.**;!org.apache.commons.collections.**;
- Use the latest MySQL Java connector.
- Apply the security configuration settings included in the ColdFusion Security documentation and review the respective Lockdown Guides for ColdFusion 2025 and 2023.
Detection Methods
FortiGuard IPS Signature (Active)
The most immediately actionable detection method comes from Fortinet's FortiGuard Labs, which released an IPS signature on the same day the vulnerability was published. The signature is cataloged as ID 60660 under the name "Adobe.ColdFusion.CVE-2026-27304.Improper.Input.Validation" and was introduced in IPS database version 36.201 on April 14, 2026. It is available in both the Regular and Extended IPS databases. The signature detects crafted requests sent to ColdFusion servers that attempt to exploit insufficient validation of user supplied input.
One important operational note: the default action for this signature profile is set to pass, so administrators should review their IPS policies to ensure active blocking is enabled where appropriate.
Vulnerability Scanning
Tenable has cataloged CVE-2026-27304 and tracks it as a Critical severity issue. However, as of the time of this writing, Tenable's plugin page reports no dedicated Nessus scanning plugin has been released yet. This is expected for newly disclosed vulnerabilities; Nessus plugins typically follow within days. Security teams using Tenable products should monitor for plugin updates and consider running authenticated version checks against ColdFusion installations in the interim.
Version Based Detection
In the absence of exploit specific network signatures on every platform, one of the most reliable detection approaches is to identify vulnerable ColdFusion instances in your environment:
- Adobe ColdFusion 2025: Update 6 and earlier are vulnerable
- Adobe ColdFusion 2023: Update 18 and earlier are vulnerable
Asset inventory and configuration management tools should be used to enumerate all ColdFusion deployments and flag any instances running below the patched update levels (Update 7 for 2025, Update 19 for 2023).
Network Level Monitoring
The Adjacent Network attack vector (AV:A) means defenders should pay particular attention to monitoring network traffic directed at ColdFusion HTTP/HTTPS endpoints from internal or adjacent network segments. While no community Snort or Suricata rules have been published for this CVE at this time, the FortiGuard IPS signature's detection of malformed or crafted requests targeting ColdFusion input validation mechanisms provides a model for what network level anomalies to watch for.
What Is Not Yet Available
As of publication day, no specific YARA rules, publicly shared indicators of compromise (file hashes, C2 IPs, domains), or open source IDS/IPS signatures from community repositories (such as Emerging Threats or Snort community rules) have been identified for this CVE. Adobe has stated in APSB26-38 that they are "not aware of any exploits in the wild" for the issues addressed in the bulletin, which means threat intelligence feeds are unlikely to carry specific IoCs at this stage.
Affected Systems and Versions
The following Adobe ColdFusion versions are confirmed vulnerable:
- ColdFusion 2025: Update 6 and all earlier versions
- ColdFusion 2023: Update 18 and all earlier versions
The patched versions are:
- ColdFusion 2025: Update 7 (build
2025,0,07,331586) - ColdFusion 2023: Update 19 (build
2023,0,19,330899)
Both standalone and JEE deployment configurations are affected. The Adjacent Network attack vector means that ColdFusion instances accessible from internal networks, shared hosting environments, or VPN connected segments are at risk even if they are not directly exposed to the public internet.
Vendor Security History
ColdFusion has a documented history as a target for threat actors seeking initial access to enterprise and government networks. In December 2023, CISA released a joint advisory confirming that threat actors had exploited Adobe ColdFusion CVE-2023-26360, an Improper Access Control vulnerability, to gain initial access to government servers. That vulnerability was subsequently added to CISA's Known Exploited Vulnerabilities catalog.
Adobe maintains a public bug bounty program through HackerOne to engage with external security researchers. CVE-2026-27304 was reported by researcher AnirudhAnand through this program. The Zero Day Initiative also tracks ColdFusion vulnerabilities and assigned CVE-2026-27304 a deployment priority of 1, their highest urgency tier.
This historical pattern of ColdFusion vulnerabilities being weaponized for real world attacks reinforces the importance of treating Priority 1 ColdFusion patches with urgency, even when no active exploitation has been confirmed at the time of disclosure.
References
- NVD: CVE-2026-27304
- CVE Record: CVE-2026-27304
- Adobe Security Bulletin APSB26-38
- Adobe ColdFusion 2025 Update 7 Release Notes
- Adobe ColdFusion 2023 Update 19 Release Notes
- Zero Day Initiative: The April 2026 Security Update Review
- FortiGuard IPS Signature 60660
- Tenable: CVE-2026-27304
- Tenable: CVE-2026-27304 Plugins
- MS ISAC Advisory: Multiple Vulnerabilities in Adobe Products
- W3Techs: ColdFusion Usage Statistics
- CISA Advisory: Threat Actors Exploiting CVE-2023-26360
- CISA Report: Threat Actors Exploit Adobe ColdFusion CVE-2023-26360
