CVE-2025-6011Vault timing side-channel username enumeration

What broke

Vault took a measurably different amount of time to reject an unknown username versus a known one. That is a timing side-channel for username enumeration, next to the explicit error leak in CVE-2025-6010. Fixed in 1.20.2.

Why it matters

Closing the error string and leaving the timing is how enumeration advisories come back a quarter later. Take both IDs in the same change.

What to do

• Upgrade. If you still expose Userpass, pad auth responses to a constant time on your reverse proxy as defense in depth.
• Prefer SSO. Enumeration only matters if the attacker can hit the login method.

After you patch

A vault compromise is not one credential, it is every credential the vault held or could issue.

• Rotate everything in scope, including secrets the vault issued dynamically during the exposure window, because a lease that was valid then may still be valid now.
• Revoke active leases and tokens, then review the audit device log for reads you cannot attribute to a known workload.
• Rotate the vault's own credentials: unseal or recovery keys, root tokens, and any authentication backend configuration that could be used to re-enter.
• Rotate downstream credentials the vault brokered, cloud roles, database users, and PKI certificates, since the point of the vault is that it can mint them. See secrets rotation and what is secrets management.

Sources

• NVD: CVE-2025-6011