CVE-2025-55163: netty DoS — Exploit & Fix

Description

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.124.Final and 4.2.4.Final, Netty is vulnerable to MadeYouReset DDoS. This is a logical vulnerability in the HTTP/2 protocol, that uses malformed HTTP/2 control frames in order to break the max concurrent streams limit - which results in resource exhaustion and distributed denial of service. This issue has been patched in versions 4.1.124.Final and 4.2.4.Final.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-770 CWE-770

Affected Products

Vendor	Product	Versions
netty	netty	< 4.1.124
netty	netty	4.2.0 — 4.2.4

References

Advisories & Patches

https://github.com/netty/netty/security/advisories/GHSA-prj3-ccx8-p6x4

Exploits

https://github.com/netty/netty/security/advisories/GHSA-prj3-ccx8-p6x4

Other References

http://www.openwall.com/lists/oss-security/2025/08/16/1 https://www.kb.cert.org/vuls/id/767506

Frequently Asked Questions

What is CVE-2025-55163? +

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.124.Final and 4.2.4.Final, Netty is vulnerable to MadeYouReset DDoS. This is a logical vulnerability in the HTTP/2 protocol, that uses malformed HTTP/2 control frames in order to break the max concurrent streams limit - which results in resource exhaustion and distributed denial of service. This issue has been patched in versions 4.1.124.Final and 4.2.4.Final. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-55163? +

CVE-2025-55163 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-55163? +

CVE-2025-55163 affects products from netty, specifically: netty. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-55163? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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