Package Instance

Apache ZooKeeper: Reverse-DNS fallback enables hostname verification bypass in ZooKeeper ZKTrustManager
Hostname verification in Apache ZooKeeper ZKTrustManager falls back to reverse DNS (PTR) when IP SAN validation fails, allowing attackers who control or spoof PTR records to impersonate ZooKeeper servers or clients with a valid certificate for the PTR name. It's important to note that attacker must present a certificate which is trusted by ZKTrustManager which makes the attack vector harder to exploit. Users are recommended to upgrade to version 3.8.6 or 3.9.5, which fixes this issue by introducing a new configuration option to disable reverse DNS lookup in client and quorum protocols.

Apache ZooKeeper: Insufficient Permission Check in AdminServer Snapshot/Restore Commands
Improper permission checks in the AdminServer allow an authenticated client with insufficient privileges to invoke the `snapshot` and `restore` commands. The intended requirement is authentication and authorization on the root path (`/`) with **ALL** permission for these operations; however, affected versions permit invocation without that level of authorization. The primary risk is disclosure of cluster state via snapshots to a lesser-privileged client.

*   **Affected:** `org.apache.zookeeper:zookeeper` 3.9.0 through 3.9.3.
*   **Fixed:** 3.9.4 (ZOOKEEPER-4964 “check permissions individually during admin server auth”).
*   **Mitigations:**
*   Disable both commands (`admin.snapshot.enabled`, `admin.restore.enabled`).
*   Disable AdminServer (`admin.enableServer`).
*   Ensure the root ACL is not open; note that ZooKeeper ACLs are not recursive.
*   Upgrade to 3.9.4.

Apache ZooKeeper: Authentication bypass with IP-based authentication in Admin Server
When using IPAuthenticationProvider in ZooKeeper Admin Server there is a possibility of Authentication Bypass by Spoofing -- this only impacts IP based authentication implemented in ZooKeeper Admin Server. Default configuration of client's IP address detection in IPAuthenticationProvider, which uses HTTP request headers, is weak and allows an attacker to bypass authentication via spoofing client's IP address in request headers. Default configuration honors X-Forwarded-For HTTP header to read client's IP address. X-Forwarded-For request header is mainly used by proxy servers to identify the client and can be easily spoofed by an attacker pretending that the request comes from a different IP address. Admin Server commands, such as snapshot and restore arbitrarily can be executed on successful exploitation which could potentially lead to information leakage or service availability issues. Users are recommended to upgrade to version 3.9.3, which fixes this issue.