Allocation of Resources Without Limits or Throttling Affecting io.netty:netty-codec-http package, versions [,4.1.138.Final)[4.2.0.Final,4.2.18.Final)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published24 Sept 2026
- disclosed10 Sept 2026
- creditYazan Balawneh, Mike Read
Introduced: 10 Sep 2026
NewCVE-2026-93491 (opens in a new tab)How to fix?
Upgrade io.netty:netty-codec-http to version 4.1.138.Final, 4.2.18.Final or higher.
Overview
io.netty:netty-codec-http is a network application framework for rapid development of maintainable high performance protocol servers & clients.
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the enqueueMethod() method of HttpServerCodec, which packs the first 32 pipelined HTTP methods into a single long and then appends every further entry to the methodOverflowQueue ArrayDeque<Byte> with no size check. An attacker can exhaust the heap by pipelining a large number of minimal requests such as GET / HTTP/1.1\r\nHost: x\r\n\r\n on a single connection, with the growth coming from the codec's own per-connection bookkeeping rather than from buffered bodies. This requires the attacker to hold the connection open while withholding socket reads, so back pressure leaves responses unflushed and the decoder runs ahead of them, accumulating entries.
Details
Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.
Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.
One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.
When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.
Two common types of DoS vulnerabilities:
High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.
Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm
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