CVE-2025-6203 Vault unauthenticated denial of service through complex json payload

What is CVE-2025-6203?

CVE-2025-6203 is a high-severity denial of service vulnerability in Hashicorp Vault, published on 28 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A malicious user may submit a specially-crafted complex payload that otherwise meets the default request size limit which results in excessive memory and CPU consumption of Vault. This may lead to a timeout in Vault’s auditing subroutine, potentially resulting in the Vault server to become unresponsive. This vulnerability, CVE-2025-6203, is fixed in Vault Community Edition 1.20.3 and Vault Enterprise 1.20.3, 1.19.9, 1.18.14, and 1.16.25.

Weakness: CWE-770

Which versions are affected by CVE-2025-6203?

4 open source packages ship an affected version, including github.com/hashicorp/vault and vault. It affects 1 product.

Products include Hashicorp Vault.

How do I fix CVE-2025-6203?

Upgrade github.com/hashicorp/vault to 1.20.3 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-6203 being exploited?

There is no known exploitation of CVE-2025-6203 in the wild and no public exploit code.

Other vulnerabilities in Hashicorp Vault

• CVE-2020-35192 Hardcoded credentials in n/a Critical 9.8
• CVE-2020-12757 Improper Input Validation in HashiCorp Vault Critical 9.8
• CVE-2025-6000 Arbitrary Remote Code Execution via Plugin Catalog Abuse Critical 9.1
• CVE-2022-40186 HashiCorp Vault vulnerable to incorrect metadata access Critical 9.1
• CVE-2022-36129 Missing authorization in n/a Critical 9.1

All Hashicorp Vault vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-vault-2025-6203, GHSA-8f82-53h8-2p34, GO-2025-3924, MINI-6j2q-v8gv-c9j2, openSUSE-SU-2025:15579-1.