What is CVE-2026-100655?

CVE-2026-100655 is a high-severity vulnerability in Netty, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-26.

How severe is CVE-2026-100655?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Netty

CVE-2026-100655

Netty (io.netty:netty-codec-http) versions up to and including 4.1.137.Final and from 4.2.0.Final through 4.2.17.Final accept an unlimited number of concurrent remote-initiated SPDY streams: SpdySessionHandler defaults localConcurrentStreams to Integer.MAX_VALUE and exposes no API to change it. A remote peer that opens a SPDY connection and sends millions of SYN_STREAM frames with FLAG_FIN=0 causes the server to allocate unbounded heap and direct memory, eventually triggering a JVM OutOfMemoryError and crashing the service. Fixed in 4.1.138.Final and 4.2.18.Final.

Published 2026-09-26.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Netty

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

github.com/netty/netty/security/advisories/GHSA-rmcw-9fcq-wjq7 (vendor-advisory)
www.vulncheck.com/advisories/netty-before-4.1.138-final-denial-of-service-via-s… (third-party-advisory)

Frequently asked questions

What is CVE-2026-100655?: CVE-2026-100655 is a high-severity vulnerability in Netty, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-26.
How severe is CVE-2026-100655?: High severity. CVSS v3 base score is 7.5 out of 10.