Resource exhaustion in Netty
CVE-2026-100656
Netty (io.netty:netty-codec-http) contains an unbounded per-connection queue growth flaw in HttpServerCodec. The codec tracks the HTTP method of each still-unanswered pipelined request; the first 32 entries are bit-packed into a single long, but every additional entry is appended to methodOverflowQueue, an ArrayDeque with no size limit and no rejection path. A remote, unauthenticated attacker who pipelines HTTP/1.1 requests on a single connection while withholding reads on their own end (preventing responses from being flushed) can grow this queue without bound, causing unbounded heap growth and denial of service. Affected versions are 4.2.0.Final through 4.2.17.Final and all releases up to and including 4.1.137.Final; the issue is fixed in 4.2.18.Final and 4.1.138.Final.
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/netty/netty/security/advisories/GHSA-pvjx-v7vp-62vq (vendor-advisory)
- www.vulncheck.com/advisories/netty-httpservercodec-unbounded-queue-growth-via-h… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100656?
- CVE-2026-100656 is a high-severity vulnerability in Netty, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-26.
- How severe is CVE-2026-100656?
- High severity. CVSS v3 base score is 7.5 out of 10.