CVE-2026-56817

8.3 HIGH 0.7% exploit odds Fix listed Other Library

What it is

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final through 4.2.15.Final and 4.1.0.Final through 4.1.135.Final, any caller that can deliver bytes to a Netty channel pipeline containing `XmlDecoder` can send XML with a `DOCTYPE` declaration to an `AsyncXMLInputFactory` instantiated with no security configuration, leaving DTD and entity handling active depending on Aalto XML async parser behavior and creating conditional XML external entity risk. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure.
Exploit odds: 0.7% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-07-21 23:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-07-30 14:48 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.7% in the next 30 days (EPSS).
Severity: 8.3 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-07-21 23:17 UTC
Last modified: 2026-07-30 14:48 UTC
Exploit probability: 0.7% · EPSS, next 30 days
Weakness: CWE-611 · XML external entity
Record status: Analyzed

Affected

Netty < 4.1.136
Netty < 4.2.16

Attack profile CVSS 4.0 · 8.3

Attack vector: Network
Complexity: Low
Attack requirements: Present
Privileges needed: None
User interaction: None
Confidentiality: High
Integrity: None
Availability: Low

Raw vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2026-56817.md and follow it. Check whether this project is affected by CVE-2026-56817. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record