CVE-2018-4939
Adobe ColdFusion Deserialization of Untrusted Data Vulnerability
Description
CVE-2018-4939 is a critical-severity deserialization of untrusted data vulnerability in Adobe ColdFusion that can lead to arbitrary code execution. The flaw affects ColdFusion 2016 Update 5 and earlier, as well as ColdFusion 11 Update 13 and earlier. An unauthenticated attacker can exploit this vulnerability remotely without any user interaction, making it particularly dangerous for internet-facing ColdFusion deployments. CISA has added CVE-2018-4939 to its Known Exploited Vulnerabilities catalog, confirming active exploitation. With an EPSS score of 73.93% (98.8th percentile), this Adobe ColdFusion deserialization vulnerability has a very high probability of exploitation.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| adobe | coldfusion | 11.0; 2016 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
- http://www.securityfocus.com/bid/103718(Third Party Advisory, VDB Entry)
- https://helpx.adobe.com/security/products/coldfusion/apsb18-14.html(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-4939(Third Party Advisory, US Government Resource)
Weakness Type
CWE-502: Deserialization of Untrusted Data
Deserialization of Untrusted Data occurs when an application deserializes data from an untrusted source without sufficient verification that the resulting data will be valid and safe. In Adobe ColdFusion, this vulnerability allows attackers to submit crafted serialized Java objects that trigger malicious operations during the deserialization process, leading directly to remote code execution on the server.
Learn more: CWE-502 — Deserialization of Untrusted Data
Impact Analysis
CVE-2018-4939 carries a CVSS 3.1 score of 9.8 (CRITICAL), representing one of the most severe vulnerability profiles possible. The deserialization vulnerability is remotely exploitable over the network with low attack complexity, requires no authentication or privileges, and demands no user interaction. Successful exploitation results in high impact to confidentiality, integrity, and availability, enabling an attacker to achieve complete system compromise with the privileges of the ColdFusion service account. The EPSS score of 73.93% (98.8th percentile) confirms that this vulnerability is among the most likely to be actively exploited, reflecting the availability of reliable exploitation techniques and ongoing attacker interest. Organizations running unpatched Adobe ColdFusion instances exposed to the internet face an extremely high risk of server compromise, data theft, and potential lateral movement into internal networks.
Exploit Maturity
CVE-2018-4939 is confirmed as actively exploited through its inclusion in the CISA Known Exploited Vulnerabilities catalog. The EPSS score of 73.93% (98.8th percentile) indicates a very high probability of exploitation activity, consistent with widespread weaponization of Java deserialization attacks against ColdFusion. Federal agencies were required to remediate this vulnerability by 2022-05-03 per CISA's binding operational directive. ColdFusion deserialization vulnerabilities have been a well-known attack vector, with mature tooling such as ysoserial providing readily available gadget chains for exploitation, making this vulnerability accessible even to less sophisticated attackers.
Remediation
- Apply vendor patches immediately as mandated by CISA KEV: Apply updates per vendor instructions. Upgrade Adobe ColdFusion 2016 past Update 5 and ColdFusion 11 past Update 13 by installing the security updates from Adobe Security Bulletin APSB18-14.
- If running ColdFusion 11 or earlier, plan a migration to a currently supported ColdFusion version, as older releases may no longer receive security updates. Verify that the latest cumulative hotfixes are applied to all ColdFusion instances.
- Restrict network access to ColdFusion administration interfaces and sensitive endpoints. Implement Web Application Firewall (WAF) rules to detect and block serialized Java object payloads in HTTP requests. Disable the RDS and external serialization endpoints if not required.
- Monitor ColdFusion logs for deserialization-related exceptions and unusual process activity. Deploy endpoint detection to identify indicators of post-exploitation behavior, such as the ColdFusion process spawning unexpected child processes or writing files to web-accessible directories.
- Implement defense-in-depth measures against deserialization attacks by configuring ColdFusion's JVM to use serialization filters (JEP 290) that restrict which classes can be deserialized. Run the ColdFusion service with minimal privileges to limit the impact of successful exploitation.
Technical Details
CVE-2018-4939 is a deserialization of untrusted data vulnerability (CWE-502) in Adobe ColdFusion 2016 Update 5 and earlier, and ColdFusion 11 Update 13 and earlier. The vulnerability exists because the application deserializes Java objects from untrusted network input without implementing adequate class restrictions or integrity verification. Attackers can craft malicious serialized Java payloads using known gadget chains that trigger arbitrary code execution during the deserialization process. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) reflects maximum exploitability: network-accessible, low complexity, no authentication required, and no user interaction needed. The resulting impact is complete compromise of confidentiality, integrity, and availability, allowing an attacker to execute commands on the server with the privileges of the ColdFusion application service account.
Frequently Asked Questions
Is CVE-2018-4939 being actively exploited?
Yes. CVE-2018-4939 is listed in the CISA Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. The EPSS score of 73.93% (98.8th percentile) indicates a very high probability of exploitation. Java deserialization attacks against ColdFusion are well-understood with mature tooling available.
What products are affected by CVE-2018-4939?
CVE-2018-4939 affects Adobe ColdFusion 2016 Update 5 and earlier versions, as well as Adobe ColdFusion 11 Update 13 and earlier versions. Both product lines require patching to address the deserialization vulnerability.
How do I fix CVE-2018-4939?
Apply the security updates from Adobe Security Bulletin APSB18-14. Upgrade ColdFusion 2016 past Update 5 and ColdFusion 11 past Update 13. Additionally, implement JVM serialization filters and restrict network access to ColdFusion administration endpoints.
How severe is CVE-2018-4939?
CVE-2018-4939 has a CVSS 3.1 score of 9.8 (CRITICAL), the highest severity rating. The combination of unauthenticated remote exploitation, no user interaction requirement, and complete system compromise capability makes this one of the most dangerous ColdFusion vulnerabilities. Immediate patching is essential.
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