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MEDIUM severity

CVE-2023-34054 — reactor-netty-core

MEDIUMFix: reactor/reactor-netty@37dc8a2

CVE-2023-34054 is a medium-severity (CVSS 5.3) vulnerability in io.projectreactor.netty:reactor-netty-core. A fix is available for io.projectreactor.netty:reactor-netty-core — see the affected versions and patch details below.

Reactor Netty HTTP Server Metrics DoS Vulnerability

Also known asGHSA-q24v-hpg3-v3jp
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.9%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs60th percentile — riskier than 60% of all scored CVEsHighest risk
0.00%0.47%0.94%1.41%0.2%0.2%0.9%0.9%0.9%May 26Oct 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected
☕io.projectreactor.netty:reactor-netty-core☕io.projectreactor.netty:reactor-netty-core

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

In Reactor Netty HTTP Server, versions 1.1.x prior to 1.1.13 and versions 1.0.x prior to 1.0.39, it is possible for a user to provide specially crafted HTTP requests that may cause a denial-of-service (DoS) condition.

Specifically, an application is vulnerable if Reactor Netty HTTP Server built-in integration with Micrometer is enabled.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenio.projectreactor.netty:reactor-netty-core≥ 1.1.0&&< 1.1.131.1.13io.projectreactor.netty:reactor-netty-core:1.1.13
☕Mavenio.projectreactor.netty:reactor-netty-core≥ 1.0.0&&< 1.0.391.0.39io.projectreactor.netty:reactor-netty-core:1.0.39

Affected Products

1 product · 2 configurations
Application
reactor nettybroadcom
≥ 1.1.0 && < 1.1.13
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update io.projectreactor.netty:reactor-netty-core to 1.1.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-34054 is resolved across your whole dependency graph.

  3. 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.

Frequently Asked Questions

In Reactor Netty HTTP Server, versions 1.1.x prior to 1.1.13 and versions 1.0.x prior to 1.0.39, it is possible for a user to provide specially crafted HTTP requests that may cause a denial-of-service (DoS) condition. Specifically, an application is vulnerable if Reactor Netty HTTP Server built-in integration with Micrometer is enabled.
O3 Security · Impact-Aware SCA

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CVE-2023-34054: reactor-netty-core DoS — Fixed in 1.1.13