An improper authorization vulnerability has been identified in Apache Kafka.

The implementation of the CONSUMERGROUPDESCRIBE (69) API validates the DESCRIBE operation on the GROUP resource instead of the READ operation that documented in the official kafka documentation and the KIP-848. This discrepancy can result in misconfigured Access Control Lists (ACLs) and unintended security postures, like granting READ permission to users who should not be able to join/sync groups, or allowing users without READ permission (but with DESCRIBE permission) to access sensitive group metadata.

The correct permission for CONSUMERGROUPDESCRIBE API is DESCRIBE GROUP so the current implementation is correct. However, the kafka documentation as well as the KIP-848 will be updated to reflect the correct permission. We advise the Kafka users to review existing group ACLs to ensure the principle of least privilege.

Information exposure vulnerability has been identified in Apache Kafka.

The NetworkClient component will output entire requests and responses information in the DEBUG log level in the logs. By default, the log level is set to INFO level. If the DEBUG level is enabled, the sensitive information will be exposed via the requests and responses output log. The entire lists of impacted requests and responses are:

AlterConfigsRequest

AlterUserScramCredentialsRequest

ExpireDelegationTokenRequest

IncrementalAlterConfigsRequest

RenewDelegationTokenRequest

SaslAuthenticateRequest

createDelegationTokenResponse

describeDelegationTokenResponse

SaslAuthenticateResponse

This issue affects Apache Kafka: from any version supported the listed API above through v3.9.1, v4.0.0. We advise the Kafka users to upgrade to v3.9.2, v4.0.1, or later to avoid this vulnerability.

A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics.

When a produce batch expires due to delivery.timeout.ms while a network request containing that batch is still in flight, the batch’s ByteBuffer is prematurely deallocated and returned to the buffer pool. If a subsequent producer batch—potentially destined for a different topic—reuses this freed buffer before the original network request completes, the buffer contents may become corrupted. This can result in messages being delivered to unintended topics without any error being reported to the producer.

Data Confidentiality: Messages intended for one topic may be delivered to a different topic, potentially exposing sensitive data to consumers who have access to the destination topic but not the intended source topic.

Data Integrity: Consumers on the receiving topic may encounter unexpected or incompatible messages, leading to deserialization failures, processing errors, and corrupted downstream data.

This issue affects Apache Kafka versions ≤ 3.9.1, ≤ 4.0.1, and ≤ 4.1.1.

Kafka users are advised to upgrade to 3.9.2, 4.0.2, 4.1.2, 4.2.0, or later to address this vulnerability.

Incorrect Implementation of Authentication Algorithm in Apache Kafka's SCRAM implementation.

Issue Summary: Apache Kafka's implementation of the Salted Challenge Response Authentication Mechanism (SCRAM) did not fully adhere to the requirements of RFC 5802 [1]. Specifically, as per RFC 5802, the server must verify that the nonce sent by the client in the second message matches the nonce sent by the server in its first message. However, Kafka's SCRAM implementation did not perform this validation.

Impact: This vulnerability is exploitable only when an attacker has plaintext access to the SCRAM authentication exchange. However, the usage of SCRAM over plaintext is strongly discouraged as it is considered an insecure practice [2]. Apache Kafka recommends deploying SCRAM exclusively with TLS encryption to protect SCRAM exchanges from interception [3]. Deployments using SCRAM with TLS are not affected by this issue.

How to Detect If You Are Impacted: If your deployment uses SCRAM authentication over plaintext communication channels (without TLS encryption), you are likely impacted. To check if TLS is enabled, review your server.properties configuration file for listeners property. If you have SASLPLAINTEXT in the listeners, then you are likely impacted.

Fix Details: The issue has been addressed by introducing nonce verification in the final message of the SCRAM authentication exchange to ensure compliance with RFC 5802.

Affected Versions: Apache Kafka versions 0.10.2.0 through 3.9.0, excluding the fixed versions below.

Fixed Versions: 3.9.0 3.8.1 3.7.2

Users are advised to upgrade to 3.7.2 or later to mitigate this issue.

Recommendations for Mitigation: Users unable to upgrade to the fixed versions can mitigate the issue by: - Using TLS with SCRAM Authentication: Always deploy SCRAM over TLS to encrypt authentication exchanges and protect against interception. - Considering Alternative Authentication Mechanisms: Evaluate alternative authentication mechanisms, such as PLAIN, Kerberos or OAuth with TLS, which provide additional layers of security.

Files or Directories Accessible to External Parties, Improper Privilege Management vulnerability in Apache Kafka Clients.

Apache Kafka Clients accept configuration data for customizing behavior, and includes ConfigProvider plugins in order to manipulate these configurations. Apache Kafka also provides FileConfigProvider, DirectoryConfigProvider, and EnvVarConfigProvider implementations which include the ability to read from disk or environment variables. In applications where Apache Kafka Clients configurations can be specified by an untrusted party, attackers may use these ConfigProviders to read arbitrary contents of the disk and environment variables.

In particular, this flaw may be used in Apache Kafka Connect to escalate from REST API access to filesystem/environment access, which may be undesirable in certain environments, including SaaS products. This issue affects Apache Kafka Clients: from 2.3.0 through 3.5.2, 3.6.2, 3.7.0.

Users with affected applications are recommended to upgrade kafka-clients to version >=3.8.0, and set the JVM system property "org.apache.kafka.automatic.config.providers=none". Users of Kafka Connect with one of the listed ConfigProvider implementations specified in their worker config are also recommended to add appropriate "allowlist.pattern" and "allowed.paths" to restrict their operation to appropriate bounds.

For users of Kafka Clients or Kafka Connect in environments that trust users with disk and environment variable access, it is not recommended to set the system property. For users of the Kafka Broker, Kafka MirrorMaker 2.0, Kafka Streams, and Kafka command-line tools, it is not recommended to set the system property.

Apache Kafka could allow a remote attacker to obtain sensitive information, caused by a timing attack flaw due to the use of "Arrays.equals" to validate a password or key. By utilizing brute-force attack techniques, an attacker could exploit this vulnerability to obtain credentials information, and use this information to launch further attacks against the affected system.

Impact If GZIP request body inflation is enabled and requests from different clients are multiplexed onto a single connection and if an attacker can send a request with a body that is received entirely by not consumed by the application, then a subsequent request on the same connection will see that body prepended to it's body.

The attacker will not see any data, but may inject data into the body of the subsequent request

CVE score is 4.8 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

Workarounds The problem can be worked around by either: - Disabling compressed request body inflation by GzipHandler. - By always fully consuming the request content before sending a response. - By adding a Connection: close to any response where the servlet does not fully consume request content.

Apache Kafka before versions 0.10.2.2, 0.11.0.3, 1.0.1 and 1.1.0 allow users to perform actions reserved for the Broker via manually created fetch requests that interfere with data replication, resulting in data loss.

External Reference:

https://lists.apache.org/thread.html/29f61337323f48c47d4b41d74b9e452bd60e65d0e5103af9a6bb2fef@%3Cusers.kafka.apache.org%3E

Upstream Patches:

https://github.com/apache/kafka/commit/d2932ad370c5b56edac9d99e6d75f199537a569f https://github.com/apache/kafka/commit/580f743c3ce633241d6076ce83fb778cea86a1f6 https://github.com/apache/kafka/commit/51f0f3ee792cf9352ce61afeca098c765cdad664

In Apache Kafka 0.10.0.0 to 0.10.2.1 and 0.11.0.0 to 0.11.0.1, authenticated Kafka clients may use impersonation via a manually crafted protocol message with SASL/PLAIN or SASL/SCRAM authentication when using the built-in PLAIN or SCRAM server implementations in Apache Kafka.