CVE-2025-6203: 
HashiCorp Vault vulnerability analysis and mitigation

A high-severity vulnerability (CVE-2025-6203) was discovered in HashiCorp Vault, affecting both Community and Enterprise editions from versions 1.15.0 up to 1.20.2. The vulnerability was disclosed on August 28, 2025, and received a CVSS score of 7.5 (High). The flaw affects Vault's handling of complex JSON requests, potentially impacting authentication, authorization, and secret delivery processes in enterprise environments (HashiCorp Discussion, Security Online).

The vulnerability stems from Vault's processing of complex JSON payloads. While Vault traditionally enforces a maxrequestsize of 32 MiB (configurable by operators), the vulnerability lies in the nested complexity of JSON structures rather than overall size. The issue is classified as CWE-770 (Allocation of Resources Without Limits or Throttling) and can trigger excessive memory and CPU consumption in Vault's auditing subroutine (NVD, HashiCorp Discussion).

When exploited, this vulnerability can cause the Vault server to become unresponsive, leading to a Denial-of-Service (DoS) condition. This can significantly disrupt authentication, authorization, and secret delivery processes in enterprise environments. The impact is particularly severe as Vault's audit devices must complete logging every interaction before a request can complete (Security Online).

HashiCorp has released patched versions: Vault Community Edition 1.20.3 and Vault Enterprise versions 1.20.3, 1.19.9, 1.18.14, and 1.16.25. Additionally, new listener configuration options have been introduced to set tighter limits on JSON payloads, including maxjsondepth, maxjsonstringvaluelength, maxjsonobjectentrycount, and maxjsonarrayelementcount. Organizations are strongly advised to upgrade to the patched versions immediately (HashiCorp Discussion).