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Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : nginx vulnerabilities (USN-8375-1)

critical Nessus Plugin ID 318631

Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8375-1 advisory.

 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)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-8375-1

Plugin Details

Severity: Critical

ID: 318631

File Name: ubuntu_USN-8375-1.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 6/4/2026

Updated: 6/4/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Critical

Score: 9.4

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:C

CVSS Score Source: CVE-2026-27654

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 5

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

CVSS Score Source: CVE-2026-27784

CVSS v4

Risk Factor: Critical

Base Score: 9.2

Threat Score: 8.2

Threat Vector: CVSS:4.0/E:P

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS Score Source: CVE-2026-9256

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-fancyindex, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-stream, p-cpe:/a:canonical:ubuntu_linux:nginx-common, p-cpe:/a:canonical:ubuntu_linux:nginx-core, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-subs-filter, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-headers-more-filter, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-uploadprogress, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-geoip, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-auth-pam, p-cpe:/a:canonical:ubuntu_linux:nginx-light, p-cpe:/a:canonical:ubuntu_linux:nginx-full, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-echo, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-geoip2, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-nchan, p-cpe:/a:canonical:ubuntu_linux:nginx-naxsi, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-dav-ext, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-xslt-filter, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-image-filter, p-cpe:/a:canonical:ubuntu_linux:nginx-naxsi-ui, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-ndk, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-perl, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:nginx-extras, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-lua, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-cache-purge, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-mail, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-rtmp, p-cpe:/a:canonical:ubuntu_linux:nginx, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:libnginx-mod-http-upstream-fair

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 6/3/2026

Vulnerability Publication Date: 8/13/2025

Reference Information

CVE: 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

IAVA: 2025-A-0615, 2026-A-0140, 2026-A-0280-S, 2026-A-0515

USN: 8375-1