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How the CVE Works
The vulnerability arises in Hashicorp Vault’s TLS certificate authentication method when a non-CA certificate is configured as a trusted certificate. Normally, Vault should strictly validate client certificates against trusted Certificate Authorities (CAs). However, due to improper validation logic, an attacker could craft a malicious certificate that bypasses checks, allowing impersonation of legitimate users. This occurs because Vault fails to enforce CA-only validation when a non-CA certificate is mistakenly marked as trusted. The flaw affects Vault’s authentication API endpoint (/auth/cert/login), where improper certificate chain verification permits unauthorized access.
DailyCVE Form
Platform: Hashicorp Vault
Version: <1.20.1, <1.19.7, <1.18.12, <1.16.23
Vulnerability: Improper Certificate Validation
Severity: Moderate
Date: Aug 1, 2025
Prediction: Patch expected by Aug 15, 2025
What Undercode Say
Check Vault version vault version Verify auth method config vault read sys/auth/cert/tune Test cert login (exploit PoC) curl --cert malicious.pem --key key.pem $VAULT_ADDR/v1/auth/cert/login
How Exploit
An attacker crafts a certificate signed by a non-CA trusted in Vault’s config. By submitting this to /auth/cert/login, Vault grants a token tied to the impersonated identity.
Protection from this CVE
- Upgrade to Vault 1.20.1, 1.19.7, 1.18.12, or 1.16.23.
- Audit trusted certificates; remove non-CA entries.
- Enforce `allow_no_ca=false` in cert auth config.
Impact
Unauthorized access to secrets via certificate spoofing. Affects multi-tenant deployments with lax cert policies.
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Reported By: github.com
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