# CVE-2026-42587: Netty: HttpContentDecompressor maxAllocation bypass via Content-Encoding: br/zstd/snappy enables decompression bomb DoS

> CVE-2026-42587: Netty: HttpContentDecompressor maxAllocation bypass via Content-Encoding: br/zstd/snappy enables decompression bomb DoS. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-42587
Last updated: 2026-09-18T13:18:21Z

- Published: 2026-05-13 18:22 UTC · Updated: 2026-09-18 13:18 UTC · Assigner: GitHub\_M
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.99%, 62th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-400

## Description

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate encodings via ZlibDecoder, but is silently ignored when the content encoding is br (Brotli), zstd, or snappy. An attacker can bypass the configured decompression limit by sending a compressed payload with Content-Encoding: br instead of Content-Encoding: gzip, causing unbounded memory allocation and out-of-memory denial of service. The same vulnerability exists in DelegatingDecompressorFrameListener for HTTP/2 connections. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

## Affected vendors and products

- io.netty: netty-codec-http
- io.netty: netty-codec-http2
- netty: netty
- Red Hat: Cryostat 4
- Red Hat: Red Hat AMQ Broker 7.13.6
- Red Hat: Red Hat AMQ Broker 7.14.1
- Red Hat: Red Hat AMQ Clients
- Red Hat: Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16
- Red Hat: Red Hat build of Apache Camel 4 for Quarkus 3
- Red Hat: Red Hat build of Apicurio Registry 3
- Red Hat: Red Hat build of Debezium 3
- Red Hat: Red Hat Build of Keycloak
- Red Hat: Red Hat Data Grid 8.6.2
- Red Hat: Red Hat Enterprise Linux AI (RHEL AI) 3
- Red Hat: Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 7
- Red Hat: Red Hat JBoss Enterprise Application Platform 7.4 ELS on RHEL 8
- Red Hat: Red Hat JBoss Enterprise Application Platform 8.1.7.GA
- Red Hat: Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 10
- Red Hat: Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 8
- Red Hat: Red Hat JBoss Enterprise Application Platform 8.1 for RHEL 9
- Red Hat: streams for Apache Kafka 2
- Red Hat: Streams for Apache Kafka 2.9.4
- Red Hat: Streams for Apache Kafka 3.2.1

## Tracked companies

- [Confluence](https://rewindex.com/company/confluence.md)
- [Jira](https://rewindex.com/company/jira.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-42587)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-42587)
- [https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv](https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-42587 · Markdown: https://rewindex.com/cve/CVE-2026-42587.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-42587 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:50:53.630Z