GMS-2023-118: Field-level security issue with .keyword fields in OpenSearch

Advisory title: Field-level security issue with .keyword fields

Affected versions:

OpenSearch 1.0.0-1.3.7 and 2.0.0-2.4.1

Patched versions:

OpenSearch 1.3.8 and 2.5.0

Impact:

There is an issue in the implementation of field-level security (FLS) and field masking where rules written to explicitly exclude fields are not correctly applied for certain queries that rely on their auto-generated .keyword fields.

This issue is only present for authenticated users with read access to the indexes containing the restricted fields.

Workaround:

FLS rules that use explicit exclusions can be written to grant explicit access instead. Policies authored in this way are not subject to this issue.

Patches:

OpenSearch versions 1.3.8 and 2.5.0 contain a fix for this issue.

For more information:

If you have any questions or comments about this advisory, please contact AWS/Amazon Security via our issue reporting page (https://aws.amazon.com/security/vulnerability-reporting/) or directly via email to aws-security@amazon.com. Please do not create a public GitHub issue.