Is CVE-2026-100655 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-100655 being exploited in the wild.

How severe is CVE-2026-100655?

High severity, with a CVSS score of 7.5, published 26 September 2026.

Which products and versions are affected?

Netty-Codec-Http up to 4.1.137.Final and 4.2.0.Final through 4.2.17.Final.

Is there a fix for CVE-2026-100655?

A patch was published on 2026-09-26: Patched in 4.1.138.Final and 4.2.18.Final Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-100655 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-100655?

Check whether you run Netty-Codec-Http at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-100655: Netty netty-codec-http denial of service in SpdySessionHandler

CVE-2026-100655 · Severity: high · CVSS 7.5 · Published 2026-09-26

Netty is a Java networking library used to build high-performance servers and network applications. The SPDY protocol handler fails to limit the number of concurrent streams a remote peer can initiate, allowing an attacker to exhaust server memory by opening millions of streams, which crashes the service.

Technologies: Netty-Codec-Http. Vendors: Netty.

Quick answers

Is CVE-2026-100655 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-100655 being exploited in the wild.
How severe is CVE-2026-100655?: High severity, with a CVSS score of 7.5, published 26 September 2026.
Which products and versions are affected?: Netty-Codec-Http up to 4.1.137.Final and 4.2.0.Final through 4.2.17.Final.
Is there a fix for CVE-2026-100655?: A patch was published on 2026-09-26: Patched in 4.1.138.Final and 4.2.18.Final Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-100655 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-100655?: Check whether you run Netty-Codec-Http at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

SpdySessionHandler defaults localConcurrentStreams to Integer.MAX_VALUE with no API to configure it. A remote attacker can send numerous SYN_STREAM frames with FLAG_FIN=0 over a SPDY connection, causing unbounded allocation of heap and direct memory until JVM OutOfMemoryError occurs. The vulnerability requires network access and affects versions 4.1.137.Final and earlier, and 4.2.0.Final through 4.2.17.Final; patches are available in 4.1.138.Final and 4.2.18.Final.

Affected products

Netty netty-codec-http up to 4.1.137.Final and 4.2.0.Final through 4.2.17.Final

Timeline

2026-09-26: disclosed
2026-09-26: patched: Patched in 4.1.138.Final and 4.2.18.Final

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.