Withdrawn by the publisher.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 a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

Affected: Maven: io.netty:netty-codec-http

## Summary

Before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore **empty CRLF lines** preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently.

## Affected Code

| File | Lines | Role | |------|-------|------| | `codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java` | 1298–1313 | `ISO_CONTROL_OR_WHITESPACE` static initialiser — marks all ISO control chars | | `codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java` | 1307–1313 | `SKIP_CONTROL_CHARS_BYTES` `ByteProcessor` — skips the entire set | | `codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java` | 1275–1289 | `LineParser.skipControlChars` — advances `readerIndex` past all matching bytes |

## Specification Analysis

### RFC 9112 §2.2 — Message Parsing

> In the interest of robustness, a server that is expecting to receive and parse a > request-line **SHOULD ignore at least one empty line (CRLF)** received prior to the > request-line.

> An HTTP/1.1 user agent **MUST NOT** preface or…

netty-4.1.135-1.1 on GA media

eclipse-vertx/vert.x: eclipse-vertx/vert.x: Denial of Service via TLS handshake with wildcard server name netty-handler: netty-handler: IPv6 subnet rule bypass due to incorrect masking operation netty-codec-haproxy: Netty-codec-haproxy: Denial of Service via malformed HAProxy message netty-handler: Netty: Denial of Service due to eager buffer allocation in TLS handshake netty-resolver-dns: Netty DNS resolver: DNS Cache Poisoning via predictable transaction IDs netty-resolver-dns: Netty: Information disclosure and data manipulation due to improper CNAME record validation netty-codec-http2: Netty: Denial of Service via uncontrolled HTTP/2 concurrent streams io.netty/netty-resolver-dns: Netty has Insufficient Bailiwick Validation for NS Records netty-codec-http2: netty-codec-http2: Denial of Service due to resource leak netty-codec-haproxy: Netty HAProxy PROXY protocol v2 codec: Denial of Service via memory leak from crafted PROXY protocol headers netty-handler: Netty: Improper trust manager handling leads to hostname verification bypass netty-codec-http: Netty: Data manipulation via request-boundary confusion in HttpObjectDecoder io.quarkus/quarkus-vertx-http: Quarkus: Authorization bypass in HTTP path-based policies via encoded characters netty-codec-http2: Netty: Denial of Service due to HTTP/2 max header size handling

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 a network application framework for development of protocol servers and clients. Prior to versions 4.1.135.Final and 4.2.15.Final, before reading the first request-line, `HttpObjectDecoder` skips every byte for which `Character.isISOControl(b)` is `true` (0x00–0x1F and 0x7F) as well as all whitespace. RFC 9112 §2.2 only asks servers to ignore empty CRLF lines preceding the request-line — a carefully scoped robustness allowance intended to handle HTTP/1.0 POST workarounds. Silently absorbing NUL bytes, SOH, STX, and other non-CRLF control characters goes significantly beyond this, and can be exploited for request-boundary confusion in pipelined or multiplexed transports where a front-end component treats those bytes differently. Versions 4.1.135.Final and 4.2.15.Final patch the issue.

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