==========================================================================
Ubuntu Security Notice USN-8563-2
July 20, 2026

nginx regression
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

USN-8563-1 introduced a regression in nginx

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

Details:

USN-8563-1 fixed vulnerabilities in nginx. One of the fixes introduced ABI
changes that could cause issues with external modules. This update reverts
the fix for CVE-2026-42533 pending further investigation.

We apologize for the inconvenience.

Original advisory 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, resulting
 in a denial of service. (CVE-2026-60005)

Update instructions:

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

Ubuntu 26.04 LTS
  nginx                           1.28.3-2ubuntu1.8
  nginx-core                      1.28.3-2ubuntu1.8
  nginx-extras                    1.28.3-2ubuntu1.8
  nginx-full                      1.28.3-2ubuntu1.8
  nginx-light                     1.28.3-2ubuntu1.8

Ubuntu 24.04 LTS
  nginx                           1.24.0-2ubuntu7.15
  nginx-core                      1.24.0-2ubuntu7.15
  nginx-extras                    1.24.0-2ubuntu7.15
  nginx-full                      1.24.0-2ubuntu7.15
  nginx-light                     1.24.0-2ubuntu7.15

Ubuntu 22.04 LTS
  nginx                           1.18.0-6ubuntu14.18
  nginx-core                      1.18.0-6ubuntu14.18
  nginx-extras                    1.18.0-6ubuntu14.18
  nginx-full                      1.18.0-6ubuntu14.18
  nginx-light                     1.18.0-6ubuntu14.18

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

References:
  https://ubuntu.com/security/notices/USN-8563-2
  https://ubuntu.com/security/notices/USN-8563-1
  https://launchpad.net/bugs/2161362

Package Information:
  https://launchpad.net/ubuntu/+source/nginx/1.28.3-2ubuntu1.8
  https://launchpad.net/ubuntu/+source/nginx/1.24.0-2ubuntu7.15
  https://launchpad.net/ubuntu/+source/nginx/1.18.0-6ubuntu14.18

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