CVE-2023-38203

CVE-2023-38203 is a critical (CVSS 9.8) deserialization-of-untrusted-data flaw (CWE-502) in Adobe ColdFusion that can lead to arbitrary code execution. It is triggered over the network when an affected ColdFusion server processes crafted untrusted serialized data, and exploitation requires no authentication and no user interaction. A successful attacker gains arbitrary code execution with high impact on confidentiality, integrity, and availability of the host. Organizations running ColdFusion 2018 (Update 17 or earlier), ColdFusion 2021 (Update 7 or earlier), or ColdFusion 2023 (Update 1 or earlier) are affected. The flaw is being actively exploited in the wild: CISA added it to the Known Exploited Vulnerabilities catalog on 2024-01-08 with known ransomware use, EPSS assigns a 96.7% probability of exploitation within 30 days (100th percentile), and Adobe has shipped out-of-band patches in response.

What to do: Upgrade all ColdFusion 2018, 2021, and 2023 installations beyond the affected levels (at least past 2018u17, 2021u7, and 2023u1, using the latest update Adobe provides in its advisory). If patching must be delayed, apply the mitigations per Adobe's instructions, restrict or remove internet exposure of ColdFusion servers, and prioritize internet-facing hosts. Because exploitation is confirmed with known ransomware use, review ColdFusion logs and affected hosts for signs of exploitation, webshells, or follow-on malware, and discontinue use of the product if mitigations are unavailable per CISA's required action.