[[security-limitations]]
== Security Limitations

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=== Plugins

Elasticsearch's plugin infrastructure is extremely flexible in terms of what can
be extended. While it opens up Elasticsearch to a wide variety of (often custom)
additional functionality, when it comes to security, this high extensibility level
comes at a cost. We have no control over the third-party plugins' code (open
source or not) and therefore we cannot guarantee their compliance with {security}.
For this reason, third-party plugins are not officially supported on clusters
with {security} enabled.

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=== Changes in Index Wildcard Behavior

Elasticsearch clusters with {security} enabled apply the `/_all` wildcard, and
all other wildcards, to the indices that the current user has privileges for, not
the set of all indices on the cluster.
While creating or retrieving aliases by providing wildcard expressions for alias names, if there are no existing authorized aliases
that match the wildcard expression provided an IndexNotFoundException is returned.

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=== Multi Document APIs

Multi get and multi term vectors API throw IndexNotFoundException when trying to access non existing indices that the user is
not authorized for. By doing that they leak information regarding the fact that the index doesn't exist, while the user is not
authorized to know anything about those indices.

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=== Filtered Index Aliases

Aliases containing filters are not a secure way to restrict access to individual
documents, due to the limitations described in <<alias-limitations, Index and Field Names Can Be Leaked When Using Aliases>>.
{security} provides a secure way to restrict access to documents through the
<<field-and-document-access-control, document-level security>> feature.

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=== Field and Document Level Security Limitations

When a user's role enables document or field level security for an index:

* The user cannot perform write operations:
** The update API isn't supported.
** Update requests included in bulk requests aren't supported.
* The request cache is disabled for search requests.

When a user's role enables document level security for an index:

* Document level security isn't applied for APIs that aren't document based.
  An example is the field stats API.
* Document level security doesn't affect global index statistics that relevancy
  scoring uses. So this means that scores are computed without taking the role
  query into account. Note that documents not matching with the role query are
  never returned.
* The `has_child` and `has_parent` queries aren't supported as query in the
  role definition. The `has_child` and `has_parent` queries can be used in the
  search API with document level security enabled.
* Any query that makes remote calls to fetch data to query by isn't supported.
  The following queries aren't supported:
** The `terms` query with terms lookup isn't supported.
** The `geo_shape` query with indexed shapes isn't supported.
** The `percolate` query isn't supported.

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[[alias-limitations]]
=== Index and Field Names Can Be Leaked When Using Aliases

Calling certain Elasticsearch APIs on an alias can potentially leak information
about indices that the user isn't authorized to access. For example, when you get
the mappings for an alias with the `_mapping` API, the response includes the
index name and mappings for each index that the alias applies to.

Until this limitation is addressed, avoid index and field names that contain
confidential or sensitive information.

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=== LDAP Realm

The <<ldap-realm, LDAP Realm>> does not currently support the discovery of nested
LDAP Groups.  For example, if a user is a member of `group_1` and `group_1` is a
member of `group_2`, only `group_1` will be discovered. However, the
<<active-directory-realm, Active Directory Realm>> *does* support transitive
group membership.