Netty (io.netty:netty-codec-http) contains an unbounded per-connection queue growth flaw in HttpServerCodec. (CVE-2026-100656)
Netty's HttpServerCodec component has a vulnerability where an unbounded queue can grow per connection due to pipelined HTTP/1.1 requests. This flaw allows a remote attacker to cause unbounded heap growth and denial of service by withholding reads, preventing responses from being flushed. The issue affects versions 4.2.0.Final through 4.2.17.Final and all releases up to and including 4.1.137.Final. It is fixed in versions 4.2.18.Final and 4.1.138.Final.
AI Analysis
Technical Summary
The vulnerability in Netty's HttpServerCodec arises from tracking HTTP methods of pipelined requests. The first 32 requests are stored efficiently, but additional requests are appended to an unbounded ArrayDeque (methodOverflowQueue) without size limits or rejection. An attacker can exploit this by sending pipelined HTTP/1.1 requests and withholding reads, causing the queue to grow indefinitely, resulting in unbounded heap memory consumption and denial of service. This affects versions 4.2.0.Final through 4.2.17.Final and all versions up to 4.1.137.Final. The issue is fixed in versions 4.2.18.Final and 4.1.138.Final.
Potential Impact
A remote, unauthenticated attacker can cause unbounded heap growth on the server by sending pipelined HTTP/1.1 requests and withholding reads, leading to denial of service due to resource exhaustion. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade to Netty versions 4.2.18.Final or later, or 4.1.138.Final or later, where this vulnerability is fixed. No other mitigation is indicated by the vendor advisory.
Netty (io.netty:netty-codec-http) contains an unbounded per-connection queue growth flaw in HttpServerCodec. (CVE-2026-100656)
Description
Netty's HttpServerCodec component has a vulnerability where an unbounded queue can grow per connection due to pipelined HTTP/1.1 requests. This flaw allows a remote attacker to cause unbounded heap growth and denial of service by withholding reads, preventing responses from being flushed. The issue affects versions 4.2.0.Final through 4.2.17.Final and all releases up to and including 4.1.137.Final. It is fixed in versions 4.2.18.Final and 4.1.138.Final.
CVSS v3.1
Score 7.5high
Affected software
pkg:maven/io.netty/netty-codec-httpRun 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 in Netty's HttpServerCodec arises from tracking HTTP methods of pipelined requests. The first 32 requests are stored efficiently, but additional requests are appended to an unbounded ArrayDeque (methodOverflowQueue) without size limits or rejection. An attacker can exploit this by sending pipelined HTTP/1.1 requests and withholding reads, causing the queue to grow indefinitely, resulting in unbounded heap memory consumption and denial of service. This affects versions 4.2.0.Final through 4.2.17.Final and all versions up to 4.1.137.Final. The issue is fixed in versions 4.2.18.Final and 4.1.138.Final.
Potential Impact
A remote, unauthenticated attacker can cause unbounded heap growth on the server by sending pipelined HTTP/1.1 requests and withholding reads, leading to denial of service due to resource exhaustion. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
Upgrade to Netty versions 4.2.18.Final or later, or 4.1.138.Final or later, where this vulnerability is fixed. No other mitigation is indicated by the vendor advisory.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-g3wj-wqf3-65v6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-100656"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6ab89be2f7a7c54106942061
Added to database: 09/27/2026, 04:30:26 UTC
Last enriched: 09/27/2026, 04:43:47 UTC
Last updated: 09/28/2026, 01:47:40 UTC
Views: 17
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.