Ubuntu nginx Critical Denial Of Service CVE-2026-49975 Fix USN-8398-3

ubuntu

June 15, 2026

nginx could be made to consume excessive resources if it received specially crafted network traffic.

Summary

nginx could be made to consume excessive resources if it received specially

crafted network traffic.

Software Description:

- nginx: small, powerful, scalable web/proxy server

Details:

USN-8398-1 fixed a vulnerability in nginx. The update caused a regression

and was temporarily reverted in USN-8398-2. This update introduces a

complete fix for CVE-2026-49975.

We apologize for the inconvenience.

Original advisory details:

It was discovered that nginx incorrectly handled certain cookie headers in

the HTTP/2 implementation. A remote attacker could possibly use this issue

to cause nginx to consume excessive resources, resulting in a denial of

service.

Topics Covered

security advisory denial of service critical Ubuntu nginx CVE-2026-49975

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
  nginx                           1.28.3-2ubuntu1.5
  nginx-core                      1.28.3-2ubuntu1.5
  nginx-extras                    1.28.3-2ubuntu1.5
  nginx-full                      1.28.3-2ubuntu1.5
  nginx-light                     1.28.3-2ubuntu1.5

Ubuntu 25.10
  nginx                           1.28.0-6ubuntu1.7
  nginx-core                      1.28.0-6ubuntu1.7
  nginx-extras                    1.28.0-6ubuntu1.7
  nginx-full                      1.28.0-6ubuntu1.7
  nginx-light                     1.28.0-6ubuntu1.7

Ubuntu 24.04 LTS
  nginx                           1.24.0-2ubuntu7.12
  nginx-core                      1.24.0-2ubuntu7.12
  nginx-extras                    1.24.0-2ubuntu7.12
  nginx-full                      1.24.0-2ubuntu7.12
  nginx-light                     1.24.0-2ubuntu7.12

Ubuntu 22.04 LTS
  nginx                           1.18.0-6ubuntu14.15
  nginx-core                      1.18.0-6ubuntu14.15
  nginx-extras                    1.18.0-6ubuntu14.15
  nginx-full                      1.18.0-6ubuntu14.15
  nginx-light                     1.18.0-6ubuntu14.15

In general, a standard system update will make all the necessary changes.