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CVE-2026-42587

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

Description (CNA)

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 (CNA)

Vendor / productVersions
netty / nettyaffected >= 4.2.0.Alpha1, < 4.2.13.Final; affected < 4.1.133.Final
io.netty / netty-codec-httpaffected >= 4.2.0.Alpha1, < 4.2.13.Final; affected < 4.1.133.Final
io.netty / netty-codec-http2affected >= 4.2.0.Alpha1, < 4.2.13.Final; affected < 4.1.133.Final

CWE

CWE-400

References

ADP enrichment

CISA-ADP

No English description supplied.

redhat-SADP

A flaw was found in Netty. A remote attacker can bypass the configured decompression limit in the HttpContentDecompressor by sending a specially crafted compressed payload using Brotli (br), Zstandard (zstd), or Snappy content encodings. This can lead to unbounded memory allocation, resulting in an out-of-memory Denial of Service (DoS) for the affected system.