(kafka) branch trunk updated: KAFKA-18766: Clarify allow.everyone.if.no.acl.found in ACL docs (#22287)

[mi...@apache.org]

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The following commit(s) were added to refs/heads/trunk by this push:
     new 4fc0a3042e4 KAFKA-18766: Clarify allow.everyone.if.no.acl.found in ACL docs (#22287)
4fc0a3042e4 is described below

commit 4fc0a3042e45c781bf37812b66618ba63de53b47
Author: Hana <60...@users.noreply.github.com>
AuthorDate: Wed May 20 18:36:33 2026 +1000

    KAFKA-18766: Clarify allow.everyone.if.no.acl.found in ACL docs (#22287)
    
    Document when the flag applies, that existing ACLs are unchanged, and
    that production clusters should prefer explicit ACLs with the default.
    
    Reviewers: Mickael Maison <mi...@gmail.com>, Sushant Mahajan <sm...@confluent.io>
    
    Co-authored-by: Hana1025 <hu...@gmail.com>
---
 docs/security/authorization-and-acls.md | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/docs/security/authorization-and-acls.md b/docs/security/authorization-and-acls.md
index 4d7abf94e67..360bb1995fd 100644
--- a/docs/security/authorization-and-acls.md
+++ b/docs/security/authorization-and-acls.md
@@ -46,7 +46,11 @@ If you prefer that resources without any ACLs be accessible by all users (instea
 allow.everyone.if.no.acl.found=true
 ```
 
-With this setting enabled, if a resource does not have any ACLs defined, Kafka will allow access to everyone. If a resource has one or more ACLs defined, those ACL rules will be enforced as usual, regardless of the setting. One can also add super users in server.properties like the following (note that the delimiter is semicolon since SSL user names may contain comma). Default PrincipalType string "User" is case sensitive. 
+With this setting enabled, if a resource does not have any ACLs defined, Kafka will allow access to everyone. If a resource has one or more ACLs defined, those ACL rules will be enforced as usual, regardless of the setting.
+
+**Note:** This flag only changes behavior when **no** ACL matches the resource. It does not weaken or skip ACL checks when any ACL exists for that resource. Because any resource that still has no ACLs is effectively open to all principals, `allow.everyone.if.no.acl.found=true` is mainly useful for development, tests, or a phased rollout while you add ACLs. For production clusters, keep the default (`false`) unless you routinely ensure every sensitive resource already has explicit ACLs, i [...]
+
+One can also add super users in server.properties like the following (note that the delimiter is semicolon since SSL user names may contain comma). Default PrincipalType string "User" is case sensitive.
 
 ```java-properties
 super.users=User:Bob;User:Alice