GHSA-q6cq-mhr2-jmr5 - Vulnerability details

8.7/10

CVSS 4.0

GHSA-q6cq-mhr2-jmr5

resolved Published 2026-07-22 Updated 2026-07-22

GitHub Advisory

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Vulnerability Data from Dependency-Track

Affected versions

5.6

5.6.1 5.6.0

5.5

5.5.17 5.5.16 5.5.15 5.5.14 5.5.13 5.5.12 5.5.11 5.5.10 5.5.9 5.5.8 5.5.7 5.5.6 5.5.5 5.5.4 5.5.3 5.5.2 5.5.1 5.5.0

5.4

5.4.11 5.4.10 5.4.9 5.4.8 5.4.7 5.4.6 5.4.5 5.4.4 5.4.3 5.4.2 5.4.1 5.4.0

Fixed in versions 5.7.0, 5.6.2, 5.5.18 and 5.4.12

Score

8.7 CVSS 4.0 GITHUB CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Description

The `HAProxyMessageDecoder` in netty's `codec-haproxy` module performs protocol version detection by reading the 13th byte of the inbound stream as a signed Java `byte` and widening it to `int` without masking. When an attacker sends a PROXY protocol v2 binary prefix (`0D 0A 0D 0A 00 0D 0A 51 55 49 54 0A`) followed by version byte `0xFF`, the sign extension produces `-1`, which collides with the decoder's "need more data" sentinel value. This collision traps the decoder in a version-detection loop where it perpetually requests more data without consuming any bytes, never instantiates the `HeaderExtractor` that enforces header size limits, and causes `ByteToMessageDecoder` to accumulate all subsequent inbound bytes into an unbounded `cumulation` buffer until the JVM exhausts its direct memory allocation.

Same vulnerability as

CVE-2026-55851 resolved according to EUVD-2026-46438

Analysis Read only

State

Justification

Recommandation

Workaround

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