CVE-2025-55163Network attack vector

Service interruption via untracked HTTP/2 resets

Published Aug 13, 2025 · Updated Nov 4, 2025

Resource exhaustion in Netty 4.1.123.Final and earlier and 4.2.0.Alpha1 through 4.2.3.Final allows remote attackers to interrupt services. Http2ConnectionHandler sends error resets through the raw frame writer instead of the connection encoder, so reset streams stop counting as active while canceled requests keep running. Exploitation requires a reachable Netty HTTP/2 server; rapid repetition consumes CPU or memory and interrupts the service.

CVSS severity8.2
High
EPSS probability1.05%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Netty 4.1.123.Final and earlier and 4.2.0.Alpha1 through 4.2.3.Final allows remote attackers to interrupt services. Http2ConnectionHandler sends error resets through the raw frame writer instead of the connection encoder, so reset streams stop counting as active while canceled requests keep running. Exploitation requires a reachable Netty HTTP/2 server; rapid repetition consumes CPU or memory and interrupts the service.

The record

CVE
CVE-2025-55163
Published
Aug 13, 2025
Updated
Nov 4, 2025
Vendor
The Netty Project
Product
Netty
Classifications
CWE-770, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.1.124.Final
  2. Affected versionversion=< 4.2.4.Final

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Netty Project · Nettyversion=< 4.1.124.Final; version=< 4.2.4.Final

Published CVSS scores

7.5National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.2GitHub, Inc. CNACVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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