8.7

CVE-2026-55851: netty Uncontrolled Resource Consumption

CVSS: 8.7v4.0HighAnalyzed
AliasesUBUNTU-CVE-2026-55851DEBIAN-CVE-2026-55851CGA-23xj-fw29-f8rm
Published 21-07-2026Last modified 23-07-2026
Open JSON

Vulnerability summary

CVE-2026-55851 is a high (CVSS 8.7) Uncontrolled Resource Consumption vulnerability in netty. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.1% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.63%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:11394-1SUSE-SU-2026:3482-1CGA-M5CW-3746-G39J

Timeline

  1. 21-07-2026
    PublishedVulnerability first disclosed.
  2. 23-07-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

9 scores · 7 sources · 2 versions

EPSS trend

Probability

0.63%

Chance of exploitation in the next 30 days

Percentile

49%

Versus all other CVEs

30-day change

+0.02 pp

From 0.61% on 18-09-2026

18-09-202618-10-2026
EPSS score
0.63%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard78 products
  • apache-activemq-artemis< 2.55.0-r1
  • apache-hop< 2.18.1-r12
  • apache-hop-fips< 2.18.1-r6
  • apache-pulsar-4.0< 4.0.12-r2
  • apache-pulsar-4.1< 4.1.3-r15
Wolfi19 products
  • apache-activemq-artemis< 2.55.0-r1
  • apache-pulsar-4.1< 4.1.3-r15
  • apache-pulsar-4.2< 4.2.3-r3
  • apicurio-registry< 3.3.0-r11
  • celeborn-0.6< 0.6.3-r12
Debian1 product
  • nettyAll versions (No fix recorded)
Io.netty1 product
  • netty-codec-haproxy≥ 4.2.0.Final, < 4.2.16.Final | ≥ 4.1.0.Final, < 4.1.136.Final
Netty1 product
  • netty≥ 4.2.0.Final, < 4.2.16.Final | ≥ 4.1.0.Final, < 4.1.136.Final | ≥ 4.1.0, < 4.1.136 | ≥ 4.2.0, < 4.2.16
Ubuntu1 product
  • nettyAll versions (No fix recorded)

6 vendors · 101 products

References

11 links
Show all 11 references