CVE-2026-42587

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 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 Software

VendorProductVersion RangeStatus
nettynetty>= 4.2.0.Alpha1, < 4.2.13.Finalaffected
nettynetty< 4.1.133.Finalaffected
io.nettynetty-codec-http>= 4.2.0.Alpha1, < 4.2.13.Finalaffected
io.nettynetty-codec-http< 4.1.133.Finalaffected
io.nettynetty-codec-http2>= 4.2.0.Alpha1, < 4.2.13.Finalaffected
io.nettynetty-codec-http2< 4.1.133.Finalaffected

Weaknesses

  • CWE-400: CWE-400: Uncontrolled Resource Consumption

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: yes
    • Technical Impact: partial

Additional References

netty: io.netty/netty-codec-http: io.netty/netty-codec-http2: Netty: Denial of Service via unbounded memory allocation in HTTP content decompression

Additional References

References