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high7.5

CVE-2026-42587

Netty: HttpContentDecompressor maxAllocation bypass when Content-Encoding set to br/zstd/snappy leads to decompression bomb DoS

Impact

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 packages

EcosystemPackageAffectedFixed in
mavenio.netty:netty-codec-http>= 4.2.0.Alpha1, <= 4.2.12.Final4.2.13.Final
mavenio.netty:netty-codec-http2>= 4.2.0.Alpha1, <= 4.2.12.Final4.2.13.Final

Affected products

VendorProductAffected versions
NettyNetty
before 4.1.133
from 4.2.0 before 4.2.13

Weakness classification

CWE-400CWE-770

References