Affected: F5 NGINX Open Source, F5 NGINX Plus, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions, Red Hat Enterprise Linux 9.4 Extended Update Support, Red Hat Enterprise Linux 9.6 Extended Update Support and 2 more

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected: Ubuntu:22.04:LTS: nginx, Ubuntu:24.04:LTS: nginx, Ubuntu:25.10: nginx

It was discovered that the nginx ngx_mail_auth_http_module module incorrectly handled certain requests. An attacker could possibly use this issue to cause nginx to crash, resulting in a denial of service. (CVE-2026-27651)

It was discovered that the nginx ngx_http_dav_module module incorrectly handled certain destination URIs. An attacker could use this issue to cause nginx to crash, resulting in a denial of service, or possibly modify source or destination names outside of the document root. (CVE-2026-27654)

It was discovered that the nginx ngx_http_mp4_module module incorrectly handled certain MP4 files. An attacker could use this issue to cause nginx to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-27784, CVE-2026-32647)

It was discovered that the nginx ngx_mail_smtp_module module incorrectly handled certain CRLF sequences. An attacker could possibly use this issue to inject arbitrary SMTP headers. (CVE-2026-28753)

It was discovered that the nginx ngx_stream_ssl_module module incorrectly handled revoked certificates. This could result in successful TLS handshakes even after an OCSP check identifies a certificate as revoked, contrary to expectations. This issue only affected Ubuntu 24.04 LTS and Ubuntu 25.10. (CVE-2026-28755)