vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2026-55833

Netty SPDY zlib header block continues decoded expansion after maxHeaderSize truncation

HIGH
7.5
CVSS Score
Published: July 20, 2026 at 11:18 PM UTC
Updated: July 23, 2026 at 01:34 PM UTC
1 product affected across 1 vendorNetty

Using netty by netty?

Get instant alerts when new vulnerabilities affect netty - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
HIGH7.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

Description

Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty SPDY header decoding continues inflating zlib-compressed header blocks after the raw header parser has exceeded `maxHeaderSize` and marked the frame truncated in `SpdyFrameCodec`, allowing a remote peer to send a small compressed `HEADERS` block that expands into much larger raw header data and causes compression-amplified CPU and allocation churn. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Netty· Nettymaven
95%
v < 4.1.136.Finalv < 4.2.16.Final4.1.0 ≤ v < 4.1.1364.2.0 ≤ v < 4.2.16
Affected range stops below 4.1.136, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.1.136.Final, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2.16.Final, so it looks safe — our inference, not a vendor statement

References (5)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/netty/netty/security/advisories/GHSA-mvh2-crg5-v77c
x_refsource_MISCPatch
Source: cverecord
https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b
x_refsource_MISCPatch
Source: cverecord
https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/netty/netty/releases/tag/netty-4.2.16.Final

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-400

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card