CVE Intelligence
Unknown Input validation

CVE-2026-111551 — Apache Kafka: Denial of service in Kafka Streams and client deserializers via unbounded memory allocation

Several Kafka deserialization paths read a size or count field from input data and use it directly to allocate an array, collection, or byte buffer, with no check against the bytes actually available. A small crafted input can therefore declare a very large size and force a multi-gigabyte allocation. The affected paths are, in Kafka Streams, ProcessorRecordContext (header count), ChangedDeserializer (varint value length), CombinedKeySchema (foreign-key length, which could also produce a negative size), ProcessorMetadata (key length), and AssignmentInfo group-assignment decoding; and, in the clients library, ListDeserializer (used by ListSerde). Impact: An attacker can trigger the oversized allocation and raise an OutOfMemoryError that crashes the affected consumer or Kafka Streams thread; the broker and the rest of the cluster are unaffected. The reachable surface depends on the path: writing a crafted record to a Streams application's internal changelog or repartition topics, or committing crafted offset metadata to its consumer group (Streams internal paths); writing a crafted record to any topic that a consumer reads with ListSerde (ListDeserializer); or, as a member of a Streams consumer group, returning crafted assignment data when elected leader (AssignmentInfo). Because a crafted record remains in its topic, the error can recur on restart. The record size limit (max.message.bytes) does not help, because the allocation is driven by a size field rather than by the input's length. Mitigation: Upgrade to Apache Kafka 4.2.2, 4.3.2, or 4.4.0. Where authorization is enabled, restrict write access to each application's internal topics and consumer group to its own principal, and restrict who can produce to topics that are consumed with ListSerde. Resolution: From Apache Kafka 4.2.2, 4.3.2, and 4.4.0: these deserialization paths validate the declared size against the remaining input before allocating and reject input that fails the check.

Published Oct 28, 2026 · Updated Oct 29, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: apache

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.22%
ahead of 13% of scored CVEs · Oct 29, 2026
Affects
Apache Software Foundation
Kafka
CVSS base
—
Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Kafka).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Apache Software Foundation Kafka ≥ 0.10.0.0 and ≤ 4.1.2≥ 4.2.0 and ≤ 4.2.1≥ 4.3.0 and ≤ 4.3.1 Vulnerable CVE Program (cve.org) e CISA ADP

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-20 · Improper Input Validation

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Received → Awaiting Analysis
    Oct 29, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Received
    Oct 28, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 28, 2026
  • Affected products added · apache software foundation/apache kafka
    Oct 28, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 28, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 28, 2026 · Alertas do Telegram
  • CVE published
    Oct 28, 2026 · apache

Source activity

Repeated readings are counted rather than listed.

  • 3× References added · Oct 28, 2026 – Oct 29, 2026
  • 1× Official description updated · Oct 28, 2026 – Oct 28, 2026

References

4 on the record

Elsewhere on this site

Apache Software Foundation
every CVE for this vendor
Input validation
same class
CWE-20
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-83525 Apache Kafka: Incorrect boolean operator in FetchSnapshot RPC handler allows authenticated network clients to crash the KRaft controller via a malformed request. 2d
  • CVE-2026-115644 Apache Kafka: Connect Admin REST API Authentication Bypass via Unapplied REST Extensions 2d
  • CVE-2026-116593 Apache Kafka: Kafka Connect configuration provider values exposed via validation REST API endpoint 2d
  • CVE-2026-114349 Apache Kafka: Denial of service via unbounded memory allocation when decoding compressed record batches 2d
  • CVE-2026-112375 Apache Kafka: Unauthorized principal can read arbitrary broker files via IncrementalAlterConfigs 2d
  • CVE-2026-111496 Apache Kafka: Kafka Streams StreamThread hang from integer overflow in stream-time punctuation 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-111551 is "Apache Kafka: Denial of service in Kafka Streams and client deserializers via unbounded memory allocation", rated Unknown. It affects Kafka (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.22% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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