How severe is CVE-2026-56745?

No CVSS score has been assigned to CVE-2026-56745 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-56745?

CVE-2026-56745 affects the following packages: io.netty:netty-codec-http (Maven), io.netty:netty-codec-http (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-56745?

Update io.netty:netty-codec-http to 4.2.16.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56745 is resolved across your whole dependency graph.

How do I detect CVE-2026-56745 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-56745 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-56745 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-56745 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-56745?

CVE-2026-56745 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 49th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-56745?

CVE-2026-56745 is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-56745 published, and has it been updated?

CVE-2026-56745 was published on July 21, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-56745 — netty-codec-http

Fix: netty/netty@5b68c61

CVE-2026-56745 is a Uncontrolled Resource Consumption vulnerability in io.netty:netty-codec-http. A fix is available for io.netty:netty-codec-http — see the affected versions and patch details below.

Netty SpdyHttpDecoder: ByteBuf Reference Leak on RST_STREAM Leads to Native Memory Exhaustion

Also known asGHSA-jppx-w49h-x2qq

Published

Jul 21, 2026

Updated

Aug 12, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs49th percentile — riskier than 49% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

☕io.netty:netty-codec-http☕io.netty:netty-codec-http

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, the SpdyHttpDecoder handler in Netty's SPDY-to-HTTP codec allocates a pooled ByteBuf when processing a client-initiated SYN_STREAM frame with FLAG_FIN=0 and stores the partially constructed FullHttpRequest in messageMap; when the remote peer sends RST_STREAM for that stream or the accumulated content exceeds maxContentLength, the decoder removes the entry but does not release the pooled ByteBuf, causing native memory exhaustion. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`io.netty:netty-codec-http`	≥ 4.2.0.Final&&< 4.2.16.Final	4.2.16.Final`io.netty:netty-codec-http:4.2.16.Final`
☕Maven	`io.netty:netty-codec-http`	≥ 4.1.0.Final&&< 4.1.136.Final	4.1.136.Final`io.netty:netty-codec-http:4.1.136.Final`

Affected Products

1 product · 2 configurations

Application

nettynetty

≥ 4.2.0 && < 4.2.16

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for io.netty:netty-codec-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update io.netty:netty-codec-http to 4.2.16.Final or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-56745 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This is an Important denial of service vulnerability in Netty's SPDY-to-HTTP codec, affecting Red Hat products that utilize vulnerable versions of Netty. A remote, unauthenticated attacker can exploit a memory leak in the `SpdyHttpDecoder` by sending specially crafted `SYN_STREAM` frames, leading to native memory…

Product	Fixed in	Advisory
Cryostat 4 on RHEL 9	`cryostat/cryostat-reports-rhel9:4.2.0-14`	RHSA-2026:68333
Red Hat AMQ Broker 7.13.6	`netty-codec-http`	RHSA-2026:66545
Red Hat AMQ Broker 7.14.1	`netty-codec-http`	RHSA-2026:66488
Red Hat Build of Apache Camel 3.33.2.SP3	`io.netty/netty-codec-http:4.1.136.Final-redhat-00001`	RHSA-2026:48118
Red Hat build of Apache Camel 4.18.3 for Spring Boot 3.5.16	`netty-codec-http`	RHSA-2026:54622
Red Hat build of Apicurio Registry 3.3.3	`netty-codec-http`	RHSA-2026:76637
Red Hat build of Quarkus 3.27.4.SP3	`io.netty/netty-codec-http:4.1.136.Final-redhat-00001`	RHSA-2026:47189
Red Hat build of Quarkus 3.33.2.SP3	`io.netty/netty-codec-http:4.1.136.Final-redhat-00001`	RHSA-2026:47172

Frequently Asked Questions

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, the `SpdyHttpDecoder` handler in Netty's SPDY-to-HTTP codec allocates a pooled `ByteBuf` when processing a client-initiated `SYN_STREAM` frame with `FLAG_FIN=0` and stores the partially constructed `FullHttpRequest` in `messageMap`; when the remote peer sends `RST_STREAM` for that stream or the accumulated content exceeds `maxContentLength`, the decoder removes the entry but does not release the pooled `ByteBuf`, causing n

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