Allocation of Resources Without Limits or Throttling Affecting io.netty:netty-codec-http3 package, versions [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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Start learning- Snyk IDSNYK-JAVA-IONETTY-20158603
- published27 Sept 2026
- disclosed26 Sept 2026
- creditmanus-use
Introduced: 26 Sep 2026
NewCVE-2026-100662 (opens in a new tab)How to fix?
Upgrade io.netty:netty-codec-http3 to version 4.2.18.Final or higher.
Overview
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling in the Insert With Literal Name handling in QpackEncoderHandler.java, which accepts a declared string-literal length of up to roughly 2 GiB for both the name (line 141) and the value (line 231) with no per-literal cap and no limit on the size of the cumulated buffer. An attacker can exhaust server heap and force an OutOfMemoryError by opening a QPACK encoder stream (type 0x02) on an HTTP/3 connection, issuing an Insert With Literal Name instruction that declares a length near that maximum, then trickling payload bytes so the decoder resets its reader index and retains the partial instruction while the cumulator grows toward the declared size. This requires a reachable HTTP/3 listener and reaching an OutOfMemoryError on a large heap takes several concurrent connections, but no non-default setting is needed, since the accumulation happens before the dynamic table state is consulted and the default server configuration has that table disabled.