# CVE-2026-111108: Apache Kafka: Broker OutOfMemoryError via array allocation amplification in code-generated protocol readers


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 28 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-ppj6-m59w-vr92

## What is CVE-2026-111108?

CVE-2026-111108 is a vulnerability in Apache Kafka, published on 28 Oct 2026. 

### Official description

Apache Kafka's code-generated protocol readers pre-size an array's collection from the element count declared by the sender. That count is checked only against the bytes remaining in the request buffer, which assumes about one byte per element; because most elements need several bytes, a request can declare far more elements than the buffer holds and still pass. For a keyed array the reader then allocates an ImplicitLinkedHashCollection of capacity (2 * count +1), so a request of a few tens of megabytes can force a heap allocation several times larger before any element is read. The pattern is emitted into every generated reader, so it affects all Kafka API types with an array field. 

Impact:

Request parsing happens before any authorization check. On a listener that does not require authentication (for example PLAINTEXT), an unauthenticated attacker can send a few concurrent requests that each declare a very large=

array length and allocate many times their wire size in broker heap, crashing the broker with an OutOfMemoryError. The reporter demonstrated three concurrent ~90 MB ProduceRequest (v3) connections exhausting a 1 GB heap (~8x amplification). On listeners that require authentication, the attacker needs valid credentials but no specific ACL, since parsing precedes authorization..

Mitigation:

Upgrade to Apache Kafka 4.2.2, 4.3.2, or 4.4.0. Until then, lowering socket.request.max.bytes and restricting network access to broker listeners reduces, but does not remove, exposure.

Resolution:

From Apache Kafka 4.2.2, 4.3.2, and 4.4.0: generated readers cap the initial array pre-allocation at MessageUtil.MAX_PREALLOCATED_ARRAY_CAPACITY (1000) and grow it on demand, and reject a declared array length above MessageUtil.MAX_ARRAY_LENGTH (1,000,000).

Weakness: CWE-789 (Memory Allocation with Excessive Size Value), CWE-770 (Allocation of Resources Without Limits or Throttling), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-111108?


## How do I fix CVE-2026-111108?

No fix has been published for CVE-2026-111108 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-111108 being exploited?

There is no known exploitation of CVE-2026-111108 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-111108 and fix it if it is affected.

What it is: CVE-2026-111108 is a vulnerability in Apache Kafka, published on 28 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-111108 in the wild and no public exploit code.

Affected product: Apache Kafka. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-111108/ (Markdown: https://insights.sbomify.com/CVE-2026-111108/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-111108
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-111108
- OSV: https://osv.dev/vulnerability/CVE-2026-111108

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-111108/
Summaries are generated and may contain mistakes; the official description above is the record.