Reactor Netty HTTP Server Denial of Service With Pipelined Requests

published 2026-08-26 2 mo ago modified 2026-09-02 2 mo ago also EUVD-2026-66831

cvss: 5.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits: 0; none known

The vulnerability occurs when a client sends HTTP/1.1 pipelined requests over a single connection, causing the Reactor Netty HTTP server to consume an excessive amount of memory. Reactor Netty 1.3.0 - 1.3.6 Reactor Netty 1.1.0 - 1.2.18 Reactor Netty 1.0.52 and earlier

Patch / fix

fixed in 1

pivotal reactor_netty 1.0.53, 1.2.19, 1.3.6.1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-47874 updated 2026-10-16 cvss 7.5

io.projectreactor.netty/reactor-netty: Reactor Netty HTTP Server: Denial of Service via pipelined HTTP/1.1 requests

Red Hat Fuse 7 reactor-netty 0.9.25.RELEASE
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 2 mo ago (2026-08-27)

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	5.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected products

Spring Reactor Netty

Classification

Weakness

CWE-770 Allocation of Resources Without Limits or Throttling

References

spring.io /security/cve-2026-47874
vendor-advisory

Sources

CVE List CVE-2026-47874
NVD CVE-2026-47874

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary