PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-47244 netty CVE debrief

CVE-2026-47244 is a vulnerability in Netty's HTTP/2 server implementation. Prior to versions 4.1.135.Final and 4.2.15.Final, the server could allocate excessive stream objects, potentially leading to resource exhaustion and amplification attacks. The issue arises from the DefaultHttp2Connection.DefaultEndpoint initializing maxActiveStreams/maxStreams to Integer.MAX_VALUE and Http2Settings not inserting SETTINGS_MAX_CONCURRENT_STREAMS by default.

Vendor
netty
Product
Unknown
CVSS
MEDIUM 5.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-12
Original CVE updated
2026-06-15
Advisory published
2026-06-12
Advisory updated
2026-06-15

Who should care

Users of Netty's HTTP/2 server implementation, especially those who have not explicitly set a limit on concurrent streams, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability is caused by the DefaultHttp2Connection.DefaultEndpoint initializing maxActiveStreams/maxStreams to Integer.MAX_VALUE. Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), the Netty HTTP/2 server advertises no limit and enforces none locally. This can lead to the creation of hundreds of thousands of long-lived stream objects, which can cause resource exhaustion and potentially be used for amplification attacks.

Defensive priority

MEDIUM

Recommended defensive actions

  • Upgrade to Netty version 4.1.135.Final or 4.2.15.Final or later.
  • Explicitly set a limit on concurrent streams using initialSettings().maxConcurrentStreams(n).

Evidence notes

The vulnerability is addressed in Netty versions 4.1.135.Final and 4.2.15.Final. Users can find more information at [ref-4], [ref-5], and [ref-6].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-47244 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-47244

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-47244 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-47244

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.