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-20154840
- published27 Sept 2026
- disclosed26 Sept 2026
- creditmanus-use
Introduced: 26 Sep 2026
NewCVE-2026-100661 (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 QpackUtil.decodePrefixedInteger, which places no bound on continuation bytes, unlike the HPACK decoder that stops at shift == 56, so an unterminated run returns -1 for buffer exhaustion and the caller returns without consuming anything. An attacker can grow the per-connection cumulator without bound to reach OutOfMemoryError, and consume event-loop CPU quadratically as every subsequent decode attempt rescans the whole buffer, by opening a client-initiated unidirectional QUIC stream and sending stream type 0x03 followed by a trigger byte such as 0xFF and an indefinite run of 0x80 continuation bytes. This requires only an established HTTP/3 connection and a client-initiated unidirectional stream, and either QPACK unidirectional stream reaches the decoder.