--- id: CVE-2026-42587 title: 'Netty is an asynchronous, event-driven network application framework' summary: >- 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 at… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-400 - CWE-770 vendor: netty product: netty affected: - netty < 4.1.133 - 'netty >= 4.2.0, < 4.2.13' patched: - netty 4.2.13 published: '2026-05-13' updated: '2026-09-18' sourceUpdated: '2026-09-18T13:18:21.533' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-42587' references: - url: 'https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv' label: security-advisories@github.com - url: 'https://access.redhat.com/errata/RHSA-2026:23808' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:24502' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:25123' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:28010' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:34608' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:36820' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:37390' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:41951' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:42644' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:49700' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:49701' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:50085' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:53644' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:53645' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:53646' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:54435' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:65126' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:66488' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:66545' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/security/cve/CVE-2026-42587' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2477220' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv' label: 134c704f-9b21-4f2e-91b3-4a467353bcc0 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42587.json label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://access.redhat.com/errata/RHSA-2026:53806' label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c - url: 'https://www.cve.org/CVERecord?id=CVE-2026-42587' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-42587' - url: 'https://access.redhat.com/errata/RHSA-2026:69459' tags: - nvd - cve.org - exploit-available - csaf - vex - red-hat epss: 0.0099 epssPercentile: 0.61061 exploitAvailable: true ssvc: exploitation: poc automatable: 'yes' technicalImpact: partial timestamp: '2026-05-13T18:43:31.138358Z' ingestedAt: '2026-07-01T15:50:58.841Z' --- ## Overview 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 - `netty < 4.1.133` - `netty >= 4.2.0, < 4.2.13` ## Remediation Upgrade past the affected range: - `netty 4.2.13` ## Vendor advisories - **RHSA-2026:49700** · Red Hat · fixed in: Red Hat JBoss EAP 8.1 for RHEL 10, Red Hat JBoss EAP 8.1 for RHEL 8, Red Hat JBoss EAP 8.1 for RHEL 9 · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49700) - **RHSA-2026:53644** · Red Hat · fixed in: Red Hat JBoss EAP 7.4 ELS for RHEL 7 Server · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53644) - **RHSA-2026:28010** · Red Hat · fixed in: Cryostat 4 on RHEL 9 · released 2026-06-22 · [advisory](https://access.redhat.com/errata/RHSA-2026:28010) - **RHSA-2026:41951** · Red Hat · fixed in: Red Hat Data Grid 8.6.2 · released 2026-07-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:41951) - **RHSA-2026:53806** · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 7.4.25 · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53806) - **RHSA-2026:50085** · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 8.1 · released 2026-08-04 · [advisory](https://access.redhat.com/errata/RHSA-2026:50085) - **RHSA-2026:42644** · Red Hat · fixed in: Red Hat OpenShift AI 2.25 · released 2026-07-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:42644) - **RHSA-2026:25123** · Red Hat · fixed in: Red Hat OpenShift Dev Spaces 3.28 · released 2026-06-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:25123) - **RHSA-2026:36820** · Red Hat · fixed in: Red Hat OpenShift Dev Spaces 3.29 · released 2026-07-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:36820) - **RHSA-2026:37390** · Red Hat · fixed in: Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16 · released 2026-07-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:37390) - **RHSA-2026:23808** · Red Hat · fixed in: Red Hat build of Quarkus 3.27.4 · released 2026-06-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:23808) - **Red Hat VEX** · Important · affected: Cryostat 4, OpenShift Serverless, Red Hat build of Apicurio Registry 2, Red Hat build of Apicurio Registry 3, Red Hat build of Debezium 3, Red Hat Build of Keycloak, … · no fix planned: Red Hat build of Apicurio Registry 2, Red Hat build of Debezium 3, Red Hat Fuse 7, Red Hat JBoss Enterprise Application Platform Expansion Pack, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42587.json) - **RHSA-2026:65126** · Red Hat · fixed in: Red Hat OpenShift AI 2.25 · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:65126) - **RHSA-2026:66545** · Red Hat · fixed in: Red Hat AMQ Broker 7.13.6 · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66545) - **RHSA-2026:66488** · Red Hat · fixed in: Red Hat AMQ Broker 7.14.1 · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66488) - **RHSA-2026:49701** · Red Hat · fixed in: Red Hat JBoss Enterprise Application Platform 8.1.7.GA · released 2026-08-03 · [advisory](https://access.redhat.com/errata/RHSA-2026:49701) - **RHSA-2026:53645** · Red Hat · fixed in: Red Hat JBoss EAP 7.4 ELS for RHEL 8 · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53645) - **RHSA-2026:53646** · Red Hat · fixed in: Red Hat JBoss EAP 7.4 ELS for RHEL 9 · released 2026-08-11 · [advisory](https://access.redhat.com/errata/RHSA-2026:53646) - **RHSA-2026:69459** · Red Hat · fixed in: AMQ Clients 2026.Q3 · released 2026-09-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:69459)