OpenBao Inserts Sensitive Information into Log File when processing malformed data

Impact

OpenBao before v2.3.0 and HashiCorp Vault as of the current v1.19.5 may leak sensitive information in logs when processing malformed data. This is separate from the earlier HCSEC-2025-09 / CVE-2025-4166.

Patches

This issue has been fixed in OpenBao v2.3.0 and later.

Workarounds

Like with HCSEC-2025-09, there is no known workaround except to ensure properly formatted requests from all clients.

Remediation

Users with the capability to search through server and audit logs for any possible exposed secrets can refer to the following snippets to aid in searching:

Audit Log

... "error":"error converting input for field \"password\": expected type 'string', got unconvertible type 'map[string]interface {}', value: '<sensitive data>'" ...

Server Log

error converting input for field "password": expected type 'string', got unconvertible type 'map[string]interface {}', value: '<sensitive data>'

If any matches are found, rotating the affected secret is advised.

References

See also: https://discuss.hashicorp.com/t/hcsec-2025-09-vault-may-expose-sensitive-information-in-error-logs-when-processing-malformed-data-with-the-kv-v2-plugin/74717

See also: https://github.com/go-viper/mapstructure/releases/tag/v2.3.0

See also: https://github.com/go-viper/mapstructure/pull/105 -> https://github.com/go-viper/mapstructure/commit/ed3f92181528ff776a0324107b8b55026e93766a