CVE-2026-111115: Apache Kafka · Broker OutOfMemoryError via Tagged-field Allocation Amplification
Affects Apache KafkaSource CVE Database V5
Not known to be exploited · fixed in 4.2.2 : patch Apache Kafka soon.
Data as of 28 Oct 2026, 20:13 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
- Patch
- Available – fixed in 4.2.2
Exploitation evidence
Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Apache Kafkaorg.apache.kafka:kafka | Affected
| Fixed in– |
MavenApache Software Foundation/org.apache.kafka:kafkapkg:maven/Apache Software Foundation/org.apache.kafka:kafkaOther threats | Affected
| Fixed in– |
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AI-suggested
Upgrade Apache Kafka to version 4.2.2, 4.3.2, or 4.4.0 where the vulnerability is fixed by proper bounds checking of tagged-field counts. Until upgrading, reduce the socket.request.max.bytes configuration to limit request size and restrict network access to broker listeners to reduce exposure. These interim measures mitigate but do not fully eliminate the risk.
Description
Apache Kafka's code-generated readers for flexible protocol versions read a tagged-field count declared by the sender and retain a RawTaggedField object for each unknown field. That count was bounded only by the outer request frame size (socket.request.max.bytes); it was not checked against the remaining buffer bytes or capped. Because each entry can be encoded in as little as two bytes (unknown tag 0, size 0), a modest request can declare tens of millions of tagged fields and force one object allocation per declared field. Flexible request headers (header version 2, used by flexible APIs such as ApiVersions v3) are parsed this way, so the amplification applies to the request header itself. Impact: The flexible request header is parsed on the network thread before authorization, request dispatch, and request-time quota accounting. A client can send a request of a few tens of megabytes whose header declares about 20 million tagged fields, forcing roughly that many RawTaggedField allocations and exhausting broker heap or inducing process-wide GC stalls, denying broker service. Because the header is parsed for pre-authentication APIs such as ApiVersions (v3), the allocation can occur before authentication; no Kafka resource ACL or quota is required. 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 bounds-check the tagged-field count for flexible-versioned messages, rejecting a negative count, a count exceeding the remaining buffer bytes, or a count exceeding a fixed maximum (10,000), before any per-field allocation.