Withdrawn by the publisher.

Affected: CleanStart: keycloak

Multiple security vulnerabilities affect the keycloak package. These issues are resolved in later releases. See references for individual vulnerability details.

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: Maven: io.netty:netty-codec-http, Maven: io.netty:netty-codec-http2

## Summary

`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.

## Details

`HttpContentDecompressor` stores the `maxAllocation` value at construction time (`HttpContentDecompressor.java:89`) and uses it in `newContentDecoder()` to create the appropriate decompression handler.

For gzip/deflate, `maxAllocation` is forwarded to `ZlibCodecFactory.newZlibDecoder()`:

```java // HttpContentDecompressor.java:101 — maxAllocation IS enforced .handlers(ZlibCodecFactory.newZlibDecoder(ZlibWrapper.GZIP, maxAllocation)) ```

`ZlibDecoder.prepareDecompressBuffer()` enforces this as a hard cap by setting the buffer's `maxCapacity` and throwing `DecompressionException` when the limit is reached:

```java // ZlibDecoder.java:68 — hard limit on buffer capacity return ctx.alloc().heapBuffer(Math.min(preferredSize, maxAllocation), maxAllocation); // ZlibDecoder.java:80 — throws when exceeded throw new DecompressionExcepti…

netty-4.1.133-1.1 on GA media

netty: io.netty/netty-handler-proxy: Netty: HTTP Header Injection via HttpProxyHandler Disabled Validation netty: Netty: High integrity impact due to improper DNS domain name constraint enforcement netty: io.netty/netty-codec-http: Netty: HTTP Request Smuggling due to improper handling of conflicting HTTP/1.0 headers netty: io.netty/netty-codec-http: Netty: Incorrect HTTP response parsing leads to data confusion netty: io.netty/netty-codec-http: io.netty/netty-codec-http2: Netty: Denial of Service via unbounded memory allocation in HTTP content decompression

Withdrawn by the publisher.

Affected: Ubuntu:Pro:14.04:LTS: netty, Ubuntu:Pro:16.04:LTS: netty, Ubuntu:Pro:18.04:LTS: netty, Ubuntu:Pro:20.04:LTS: netty, Ubuntu:Pro:22.04:LTS: netty, Ubuntu:Pro:24.04:LTS: netty, Ubuntu:25.10: netty, Ubuntu:Pro:26.04:LTS: netty

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.

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Netty ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren, vertrauliche Informationen offenzulegen oder einen Denial-of-Service-Zustand zu verursachen.