docs: correct auth jwt role requirements

website/content/api-docs/auth/jwt.mdx

@@ -112,8 +112,8 @@ entities attempting to login. At least one of the bound values must be set.
 - `name` `(string: <required>)` - Name of the role.
 - `role_type` `(string: <optional>)` - Type of role, either "oidc" (default) or "jwt".
 - `bound_audiences` `(array: <optional>)` - List of `aud` claims to match against.
-  Any match is sufficient. For "jwt" roles, at least one of `bound_audiences`, `bound_subject`,
-  `bound_claims` or `token_bound_cidrs` is required. Optional for "oidc" roles.
+  Any match is sufficient. Required for "jwt" roles if the JWT has an `aud`
+  claim. Optional for "oidc" roles.
 - `user_claim` `(string: <required>)` - The claim to use to uniquely identify
   the user; this will be used as the name for the Identity entity alias created
   due to a successful login. The claim value must be a string.

website/content/docs/auth/jwt/index.mdx

@@ -178,8 +178,13 @@ only needs to validate the provided JWT.
 
 ### JWT verification
 
-JWT signatures will be verified against public keys from the issuer. This process can be done in
-three different ways, though only one method may be configured for a single backend:
+JWT signatures will be verified against public keys from the issuer. You can
+configure JWT signature verifcation in several different ways, though only one
+method may be configured for a single backend. If multiple methods are needed,
+another instance of the backend can be mounted and configured at a different
+path.
+
+You can configure public keys using one of the following methods:
 
 - **Static Keys**. A set of public keys is stored directly in the backend configuration. See the
   [jwt_validation_pubkeys](/vault/api-docs/auth/jwt#jwt_validation_pubkeys) 
@@ -201,8 +206,9 @@ three different ways, though only one method may be configured for a single back
   and [oidc_discovery_ca_pem](/vault/api-docs/auth/jwt#oidc_discovery_ca_pem) configuration 
   options.
 
-If multiple methods are needed, another instance of the backend can be mounted and configured
-at a different path.
+Once the JWT signatures are verified, the JWT's `aud` claim is checked. If the
+JWT's `aud` claim is set, the role's `bound_audiences` must match at least one
+of the JWT's `aud` claims.
 
 ### Via the CLI
 
@@ -308,10 +314,13 @@ management tool.
 Once a JWT has been validated as being properly signed and not expired, the
 authorization flow will validate that any configured "bound" parameters match.
 In some cases there are dedicated parameters, for example `bound_subject`,
-which must match the JWT's `sub` parameter. A role may also be configured to
-check arbitrary claims through the `bound_claims` map. The map contains a set
-of claims and their required values. For example, assume `bound_claims` is set
-to:
+which must match the JWT's `sub` claim. For roles of type "jwt", the
+`bound_audiences` parameter is required if the JWT's `aud` claim is set and it
+must match at least one of the JWT's `aud` claims.
+
+A role may also be configured to check arbitrary claims through the
+`bound_claims` map. The map contains a set of claims and their required values.
+For example, assume `bound_claims` is set to:
 
 ```json
 {

website/content/docs/upgrading/upgrade-to-1.16.x.mdx

@@ -81,6 +81,22 @@ userattr="userprincipalname"
 Refer to the [LDAP auth method (API)](/vault/api-docs/auth/ldap) page for
 more details on the configuration.
 
+### JWT auth login requires bound audiences on the role
+
+JWT auth roles of type "jwt" require the bound_audiences claim to match at
+least one of the JWT's aud claims. The JWT's aud claim can be a single string
+or a list of strings as per
+[RFC 7519 Section 4.1.3](https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.3).
+Prior to 1.16.3, the JWT auth method would ignore token aud claims that were
+not a list of strings.
+
+The consequence of not configuring this correctly means users may not be able
+to login to Vault. To fix the issue, update the role's `bound_audiences`
+parameter to match the `aud` claim on the JWT.
+
+Refer to the [JWT auth method (API)](/vault/api-docs/auth/jwt) page for
+more details on the configuration.
+
 ## Known issues and workarounds
 
 @include 'known-issues/1_16-jwt_auth_config.mdx'