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[USN-8375-1] nginx vulnerabilities

Posted on 03 June 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8375-1
June 03, 2026

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

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS

Summary:

Several security issues were fixed in nginx.

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

Details:

It was discovered that the nginx ngx_mail_smtp_module module incorrectly
handled certain memory operations when doing SMTP authentication. This
could possibly result in sensitive information being sent to the
authentication server. (CVE-2025-53859)

It was discovered that nginx incorrectly handled proxying to upstream TLS
servers. An attacker could possibly use this issue to insert plain text
data into the response from an upstream proxied server. (CVE-2026-1642)

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 nginx contained a use-after-free vulnerability in
the ngx_http_ssl_module module when client certificate verification and
OCSP validation were enabled. A remote attacker could use this issue to
cause nginx to crash, resulting in a denial of service, or possibly modify
data in memory. (CVE-2026-40701)

It was discovered that nginx did not properly handle certain proxied
responses in the ngx_http_charset_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-2026-42934)

It was discovered that the nginx ngx_http_rewrite_module component
incorrectly handled certain rewrite directives. A remote attacker could use
this issue to cause nginx to crash, resulting in a denial of service, or
possibly execute arbitrary code. (CVE-2026-42945)

It was discovered that nginx did not properly process certain SCGI and
uWSGI responses. An attacker able to perform a machine-in-the-middle attack
could possibly use this issue to obtain sensitive information or cause
nginx to crash, resulting in a denial of service. (CVE-2026-42946)

It was discovered that nginx incorrectly handled certain rewrite rules in
the ngx_http_rewrite_module module. A remote attacker could use this issue
to cause nginx to crash, resulting in a denial of service, or possibly
execute arbitrary code. (CVE-2026-9256)

Update instructions:

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

Ubuntu 20.04 LTS
libnginx-mod-http-headers-more-filter 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
libnginx-mod-http-lua 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
libnginx-mod-mail 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
libnginx-mod-nchan 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
libnginx-mod-rtmp 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
nginx 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
nginx-core 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
nginx-extras 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
nginx-full 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro
nginx-light 1.18.0-0ubuntu1.7+esm1
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libnginx-mod-http-auth-pam 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-cache-purge 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-dav-ext 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-echo 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-fancyindex 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-geoip 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-headers-more-filter 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-image-filter 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-lua 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-ndk 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-perl 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-subs-filter 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-uploadprogress 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-upstream-fair 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-http-xslt-filter 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-mail 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-nchan 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-rtmp 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
libnginx-mod-stream 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
nginx 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
nginx-core 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
nginx-extras 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
nginx-full 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro
nginx-light 1.14.0-0ubuntu1.11+esm2
Available with Ubuntu Pro

Ubuntu 16.04 LTS
nginx 1.10.3-0ubuntu0.16.04.5+esm7
Available with Ubuntu Pro
nginx-core 1.10.3-0ubuntu0.16.04.5+esm7
Available with Ubuntu Pro
nginx-extras 1.10.3-0ubuntu0.16.04.5+esm7
Available with Ubuntu Pro
nginx-full 1.10.3-0ubuntu0.16.04.5+esm7
Available with Ubuntu Pro
nginx-light 1.10.3-0ubuntu0.16.04.5+esm7
Available with Ubuntu Pro

Ubuntu 14.04 LTS
nginx 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-common 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-core 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-extras 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-full 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-light 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro
nginx-naxsi 1.4.6-1ubuntu3.9+esm6
Available with Ubuntu Pro

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

References:
https://ubuntu.com/security/notices/USN-8375-1
CVE-2025-53859, CVE-2026-1642, CVE-2026-27651, CVE-2026-27654,
CVE-2026-27784, CVE-2026-28753, CVE-2026-32647, CVE-2026-40701,
CVE-2026-42934, CVE-2026-42945, CVE-2026-42946, CVE-2026-9256

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