CVE catalog

CVE-2026-55851

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.

[CVE catalog]

Severity
High · CVSS 8.7
Published
Source
[NVD] · [CVE record]
EPSS
0.63% · Oct 25, 2026

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the `HAProxyMessageDecoder` in Netty's `codec-haproxy` module performs protocol version detection by reading the 13th byte as a signed Java `byte` and widening it to `int` without masking; a PROXY protocol v2 binary prefix followed by version byte `0xFF` sign-extends to `-1`, collides with the decoder's need-more-data sentinel, and causes `ByteToMessageDecoder` to accumulate inbound bytes in an unbounded `cumulation` buffer until direct memory is exhausted. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

DistributionPackageReleaseVersionStatus
Debiannettysid1:4.1.48-16vulnerable
Debiannettyforky1:4.1.48-16vulnerable
Debiannettytrixie1:4.1.48-10+deb13u1vulnerable
Debiannettytrixie-security1:4.1.48-10+deb13u1vulnerable
Debiannettybookworm1:4.1.48-7+deb12u2vulnerable
Debiannettybookworm-security1:4.1.48-7+deb12u2vulnerable
Mavenio.netty:netty-codec-haproxyNot reported4.2.16.Finalfixed
Mavenio.netty:netty-codec-haproxyNot reported4.1.136.Finalfixed

Fixed-version evidence

DistributionPackageTypeReleaseFixed versionUrgencyOriginBugs
Debiannettysourcesid(unfixed)not yet assignedNot reported[1142680]
Debiannettysourceforky(unfixed)not yet assignedNot reported[1142680]
Debiannettysourcetrixie(unfixed)not yet assignedNot reported[1142680]
Debiannettysourcebookworm(unfixed)not yet assignedNot reported[1142680]
Mavenio.netty:netty-codec-haproxymavenNot reported4.2.16.FinalNot reportedNot reportedNot reported
Mavenio.netty:netty-codec-haproxymavenNot reported4.1.136.FinalNot reportedNot reportedNot reported

[Debian bug #1142680]

OpenFactory catalog packages

[Debian 12 (Bookworm)]

  • [libnetty-java]Affected

    Source package: [netty]

    Details (4)

    • 1:4.1.48-7+deb12u2 · all · bookworm

      Affected

      nvd · netty · debian · bookworm; nvd · netty · debian · 12

    • 1:4.1.48-7+deb12u2 · all · bookworm

      Affected

      nvd · netty · debian · bookworm; nvd · netty · debian · 12

    • 1:4.1.48-7+deb12u2 · all · bookworm-security

      Affected

      nvd · netty · debian · bookworm; nvd · netty · debian · 12

    • 1:4.1.48-7+deb12u2 · all · bookworm-security

      Affected

      nvd · netty · debian · bookworm; nvd · netty · debian · 12

[Debian 13 (Trixie)]

  • [libnetty-java]Affected

    Source package: [netty]

    Details (4)

    • 1:4.1.48-10+deb13u1 · all · trixie

      Affected

      nvd · netty · debian · 13

    • 1:4.1.48-10+deb13u1 · all · trixie

      Affected

      nvd · netty · debian · 13

    • 1:4.1.48-10+deb13u1 · all · trixie-security

      Affected

      nvd · netty · debian · 13

    • 1:4.1.48-10+deb13u1 · all · trixie-security

      Affected

      nvd · netty · debian · 13

Observed:

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]