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Ubuntu 26.04 nginx Critical Denial of Service Vuln 8563-1

ubuntu
Calendar Grey July 20, 2026
Scroller Ubuntu
Several security issues in nginx fixed for Ubuntu 26.04, 24.04 and 22.04 LTS impact functionality and security.
Several security issues were fixed in nginx.

Summary

Several security issues were fixed in nginx.

Software Description:

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

Details:

It was discovered that nginx incorrectly handled certain map directives

using regex matching and capture variables. A remote attacker could use

this issue to cause nginx to crash, resulting in a denial of service, or

possibly execute arbitrary code. (CVE-2026-42533)

It was discovered that nginx had a use-after-free vulnerability in the

ngx_http_ssi_module module when configured with Server-Side Includes,

proxy_pass, and proxy buffering disabled directives. An attacker able to

intercept traffic and control responses from an upstream server could

possibly use this issue to cause nginx to crash, resulting in a denial of

service. (CVE-2026-56434)

It was discovered that nginx incorrectly handled certain requests in the

ngx_http_slice_module module. A remote attacker could possibly use this

issue to obtain sensitive information or cause nginx to crash, resu...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory denial of service critical arbitrary code execution Ubuntu nginx

Update Instructions

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

Ubuntu 26.04 LTS
  nginx                           1.28.3-2ubuntu1.7
  nginx-core                      1.28.3-2ubuntu1.7
  nginx-extras                    1.28.3-2ubuntu1.7
  nginx-full                      1.28.3-2ubuntu1.7
  nginx-light                     1.28.3-2ubuntu1.7

Ubuntu 24.04 LTS
  nginx                           1.24.0-2ubuntu7.14
  nginx-core                      1.24.0-2ubuntu7.14
  nginx-extras                    1.24.0-2ubuntu7.14
  nginx-full                      1.24.0-2ubuntu7.14
  nginx-light                     1.24.0-2ubuntu7.14

Ubuntu 22.04 LTS
  nginx                           1.18.0-6ubuntu14.17
  nginx-core                      1.18.0-6ubuntu14.17
  nginx-extras                    1.18.0-6ubuntu14.17
  nginx-full                      1.18.0-6ubuntu14.17
  nginx-light                     1.18.0-6ubuntu14.17

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

References

https://ubuntu.com/security/notices/USN-8563-1

CVE-2026-42533, CVE-2026-56434, CVE-2026-60005

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8563-1

Topics%20covered

Topics Covered

security advisory denial of service critical arbitrary code execution Ubuntu nginx

Package Information

https://launchpad.net/ubuntu/+source/nginx/1.28.3-2ubuntu1.7
https://launchpad.net/ubuntu/+source/nginx/1.24.0-2ubuntu7.14
https://launchpad.net/ubuntu/+source/nginx/1.18.0-6ubuntu14.17

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