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

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Summary

CVECVE-2026-42587
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-13 19:17:24 UTC
Updated2026-05-13 19:17:24 UTC
DescriptionNetty 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-400 | CWE-400 CWE-400: Uncontrolled Resource Consumption

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Netty Netty affected >= 4.2.0.Alpha1, < 4.2.13.Final Not specified
CNA Netty Netty affected < 4.1.133.Final Not specified
CNA Io.netty Netty-codec-http affected >= 4.2.0.Alpha1, < 4.2.13.Final Not specified
CNA Io.netty Netty-codec-http affected < 4.1.133.Final Not specified
CNA Io.netty Netty-codec-http2 affected >= 4.2.0.Alpha1, < 4.2.13.Final Not specified
CNA Io.netty Netty-codec-http2 affected < 4.1.133.Final Not specified

References

ReferenceSourceLinkTags
github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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