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CVE-2026-33871

HIGHCVSS 8.7/10EPSS 0.65%

Last modified

CVE-2026-33871 is a high-severity vulnerability rated 8.7/10 on the CVSS scale. Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. EPSS estimates a 0.65% chance of exploitation in the next 30 days.

Description

Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.

Metrics

CVSS 3.1
7.5/10

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

CVSS 4.0
8.7/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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

EPSS Probability
0.65%

46.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
NettyNetty< 4.1.132
NettyNetty>= 4.2.0, < 4.2.10

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-33871?
Netty is an asynchronous, event-driven network application framework. In versions prior to 4.1.132.Final and 4.2.10.Final, a remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server's lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive. Versions 4.1.132.Final and 4.2.10.Final fix the issue.
How severe is CVE-2026-33871?
CVE-2026-33871 has a CVSS score of 8.7/10 (HIGH severity). The EPSS model estimates a 0.65% probability of exploitation in the next 30 days.
How do I fix CVE-2026-33871?
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.

Are you affected by CVE-2026-33871?

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

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Source: NVD / NIST