Atomicorp WAF Research Note: CVE-2023-38203

Adobe ColdFusion - Deserialization of Untrusted Data

CVE Details

• Already protected by existing Atomicorp WAF rules
• Protection status: Understanding Atomicorp WAF Protection Status
• CVE: CVE-2023-38203
• Name: Adobe ColdFusion - Deserialization of Untrusted Data
• Severity: Critical
• CVSS: 9.8 (v3.1) (Critical)
• CVSS version: 3.1
• CVSS source: adobe CNA
• CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • Attack vector: Network
  • Attack complexity: Low
  • Privileges required: None
  • User interaction: None
  • Scope: Unchanged
  • Confidentiality impact: High
  • Integrity impact: High
  • Availability impact: High
• CWE: CWE-502 — Deserialization of Untrusted Data
• Related CAPEC attack patterns (via MITRE CWE relationships): CAPEC-586 (opens in a new tab)
• Vendor: adobe
• Vulnerable product: coldfusion
• CVE published: 2023-07-20
• CVE last modified: 2026-06-17
• Affected versions (NVD configurations):
  • coldfusion: 2018
  • coldfusion: 2018 update1
  • coldfusion: 2018 update10
  • coldfusion: 2018 update11
  • coldfusion: 2018 update12
  • coldfusion: 2018 update13
  • coldfusion: 2018 update14
  • coldfusion: 2018 update15
  • coldfusion: 2018 update16
  • coldfusion: 2018 update17
  • coldfusion: 2018 update2
  • coldfusion: 2018 update3
  • coldfusion: 2018 update4
  • coldfusion: 2018 update5
  • coldfusion: 2018 update6
  • coldfusion: 2018 update7
  • coldfusion: 2018 update8
  • coldfusion: 2018 update9
  • coldfusion: 2021
  • coldfusion: 2021 update1
  • coldfusion: 2021 update2
  • coldfusion: 2021 update3
  • coldfusion: 2021 update4
  • coldfusion: 2021 update5
  • coldfusion: 2021 update6
  • coldfusion: 2021 update7
  • coldfusion: 2023
  • coldfusion: 2023 update1
• EPSS: 0.9672; 99.9th percentile (FIRST (opens in a new tab) )
• CISA KEV: Listed (added 2024-01-08)
  • Known ransomware campaign use: Known
• Latest Update: 2026-09-06
• Selected Rule IDs observed: 344370 , 344380 , 350147
• Matching rules: 3; rules with blocking actions: 3
• Would-block Rule IDs: 344370 , 344380 , 350147
• Request surfaces inspected: JSON request data, Request argument names, Request arguments, Request body, Request cookies, SOAP request data, XML request data

Vulnerability Description

Adobe ColdFusion versions 2018u17 (and earlier), 2021u7 (and earlier) and 2023u1 (and earlier) are affected by a Deserialization of Untrusted Data vulnerability that could result in Arbitrary code execution. Exploitation of this issue does not require user interaction.

Recommended Actions

1. Maintain the observed Atomicorp protections. Keep your Atomicorp commercial rules current and confirm that the selected observed rules (344370 , 344380 , 350147 ) have not been locally disabled. Atomicorp commercial rules are enabled by default. If you use Atomic WAF, review the applicable policy and rule settings.

2. Apply the vendor’s remediation. WAF protection is defense in depth and does not replace upgrading or following the affected vendor’s guidance.

   • Affected versions: Adobe ColdFusion versions through cf2023U1.
   • The CVE record does not include written upgrade or workaround instructions, but it does publish the following patch or mitigation reference:
     • Patch or mitigation information (opens in a new tab)
   • CISA KEV required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
   • CISA KEV federal remediation due date: 2024-01-29

3. Validate after changes. Confirm rule updates are current, review WAF events for the affected application, and test application behavior after vendor upgrades, mitigations, or local policy changes.

Research Notes

Atomicorp WAF protections are designed around attack techniques and exploit behaviors, allowing existing protections to apply across multiple vulnerabilities without requiring a unique rule for every CVE.

Public Vulnerability References

• NVD (opens in a new tab)
• CVE Record (opens in a new tab)
• Vendor advisory: https://helpx.adobe.com/security/products/coldfusion/apsb23-41.html (opens in a new tab)
• Exploit or technical research: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-38203 (opens in a new tab)

MITRE ATT&CK Context

The following mappings are published by the MITRE Center for Threat-Informed Defense and describe exploitation behavior or potential impact; they do not claim that a WAF rule implements the ATT&CK technique.

• Primary Impact: T1105 — Ingress Tool Transfer (opens in a new tab)
• Exploitation Technique: T1190 — Exploit Public-Facing Application (opens in a new tab)

Test or Research Source

• Source: http/cves/2023/CVE-2023-38203.yaml (opens in a new tab)
• Tags: adobe, coldfusion, cve, cve2023, deserialization, kev, rce, vkev, vuln

Research Note Context

This research note documents exploit-technique analysis associated with this vulnerability and references Atomicorp WAF protections observed during engineering review, testing, or validation activities.

Atomicorp security controls are generally designed to identify and mitigate attack techniques and exploit behaviors rather than individual CVE identifiers. As a result, protections developed for one vulnerability may also apply to related attack variants and future vulnerabilities using similar techniques.

Learn More

Atomicorp develops commercially supported security technologies for web applications, servers, endpoints, workloads, and legacy enterprise platforms.

Organizations interested in protecting systems against exploit techniques associated with vulnerabilities such as this one can learn more about:

• Atomic ModSecurity Rules: commercially maintained WAF rules for ModSecurity deployments, including protections for web attacks, bots, scanners, malware, exploitation attempts, and emerging vulnerability classes.
• Atomic WAF: an enterprise web application firewall with Atomicorp rules, centralized management, reporting, authentication controls, and operational tooling.
• Atomic ModSecurity Integrator: a special licensing option for MSPs, MSSPs, OEMs, VARs, reverse proxy providers, and other integrators who want to incorporate Atomicorp ModSecurity rule technology into their own products or services.
• Atomic OSSEC: an enterprise OSSEC-based intrusion detection, compliance, and security monitoring platform.
• Atomic Protector: workload protection for Linux, web, cloud, data center, and hybrid environments.

For additional information, product evaluations, or technical discussions, visit https://www.atomicorp.com/ or https://modsecurity.io/ (opens in a new tab) .