Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption… (CVE-2026-100662)
Netty's HTTP/3 codec versions 4.2.0.Final through 4.2.17.Final have a vulnerability in the QPACK encoder-stream instruction decoder that allows an attacker to cause uncontrolled resource consumption. This can lead to unbounded heap growth and an OutOfMemoryError, resulting in denial of service. The issue is fixed in version 4.2.18.Final.
AI Analysis
Technical Summary
The vulnerability exists in the QpackEncoderHandler of Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final. The handler accepts attacker-declared string-literal lengths up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the "Insert With Literal Name" instruction without enforcing per-instruction or per-literal length caps or cumulation-size limits. Existing HTTP/3 limits do not apply to this handler. A remote unauthenticated peer can declare a very large literal length and send fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the buffer indefinitely. This triggers large byte-array allocations leading to unbounded heap growth and OutOfMemoryError, resulting in denial of service. The vulnerability is fixed in version 4.2.18.Final.
Potential Impact
An unauthenticated remote attacker with an established HTTP/3 connection can cause the server to allocate excessive memory, leading to unbounded heap growth and an OutOfMemoryError. This results in denial of service against the affected Netty HTTP/3 server.
Mitigation Recommendations
Upgrade to Netty HTTP/3 codec version 4.2.18.Final or later, where this vulnerability is fixed. No other mitigations are indicated.
Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption… (CVE-2026-100662)
Description
Netty's HTTP/3 codec versions 4.2.0.Final through 4.2.17.Final have a vulnerability in the QPACK encoder-stream instruction decoder that allows an attacker to cause uncontrolled resource consumption. This can lead to unbounded heap growth and an OutOfMemoryError, resulting in denial of service. The issue is fixed in version 4.2.18.Final.
CVSS v3.1
Score 7.5high
Affected software
pkg:maven/io.netty/netty-codec-http3Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability exists in the QpackEncoderHandler of Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final. The handler accepts attacker-declared string-literal lengths up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the "Insert With Literal Name" instruction without enforcing per-instruction or per-literal length caps or cumulation-size limits. Existing HTTP/3 limits do not apply to this handler. A remote unauthenticated peer can declare a very large literal length and send fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the buffer indefinitely. This triggers large byte-array allocations leading to unbounded heap growth and OutOfMemoryError, resulting in denial of service. The vulnerability is fixed in version 4.2.18.Final.
Potential Impact
An unauthenticated remote attacker with an established HTTP/3 connection can cause the server to allocate excessive memory, leading to unbounded heap growth and an OutOfMemoryError. This results in denial of service against the affected Netty HTTP/3 server.
Mitigation Recommendations
Upgrade to Netty HTTP/3 codec version 4.2.18.Final or later, where this vulnerability is fixed. No other mitigations are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-w648-8654-gr82
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-100662"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6ab89be0f7a7c54106942057
Added to database: 09/27/2026, 04:30:24 UTC
Last enriched: 09/27/2026, 04:43:17 UTC
Last updated: 09/28/2026, 01:47:40 UTC
Views: 18
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