Package Instance

Apache ZooKeeper has improper handling of configuration values
Improper handling of configuration values in ZKConfig in Apache ZooKeeper 3.8.5 and 3.9.4 on all platforms allows an attacker to expose sensitive information stored in client configuration in the client's logfile. Configuration values are exposed at INFO level logging rendering potential production systems affected by the issue. Users are recommended to upgrade to version 3.8.6 or 3.9.5 which fixes this issue.

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.

Missing Authorization
No authentication/authorization is enforced when a server attempts to join a quorum in Apache ZooKeeper. As a result an arbitrary end point could join the cluster and begin propagating counterfeit changes to the leader.

Authorization Bypass Through User-Controlled Key vulnerability in Apache ZooKeeper. If SASL Quorum Peer authentication is enabled in ZooKeeper (quorum.auth.enableSasl=true), the authorization is done by verifying that the instance part in SASL authentication ID is listed in zoo.cfg server list. The instance part in SASL auth ID is optional and if it's missing, like 'eve@EXAMPLE.COM', the authorization check will be skipped. As a result an arbitrary endpoint could join the cluster and begin propagating counterfeit changes to the leader, essentially giving it complete read-write access to the data tree. Quorum Peer authentication is not enabled by default.

Users are recommended to upgrade to version 3.9.1, 3.8.3, 3.7.2, which fixes the issue.

Alternately ensure the ensemble election/quorum communication is protected by a firewall as this will mitigate the issue.

See the documentation for more details on correct cluster administration.

Information disclosure
ZooKeeper's `getACL()` command does not check any permission when retrieves the ACLs of the requested node and returns all information contained in the ACL Id field as plaintext string. `DigestAuthenticationProvider` overloads the Id field with the hash value that is used for user authentication. As a consequence, if Digest Authentication is in use, the unsalted hash value will be disclosed by `getACL()` request for unauthenticated or unprivileged users.

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.

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.