UBUNTU-CVE-2026-56434

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UBUNTU-CVE-2026-56434

Summary:

Details: NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

References: https://ubuntu.com/security/CVE-2026-56434, https://www.cve.org/CVERecord?id=CVE-2026-56434, https://my.f5.com/manage/s/article/K000162098, https://ubuntu.com/security/notices/USN-8563-1