CVE-2026-100656

HIGHCVSS 7.5/10

Last modified

CVE-2026-100656 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.

Description

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.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nettynetty>= 4.2.0.Final, < 4.2.18.Final
nettynetty< 4.1.138.Final

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is 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.
How severe is CVE-2026-100656?
CVE-2026-100656 has a CVSS score of 7.5/10 (HIGH severity).
How do I fix CVE-2026-100656?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

Are you affected by CVE-2026-100656?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST