Out-of-bounds read in NGINX Plus and NGINX Open Source - CVE-2025-53859

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Main Vulnerability Database Vulnerabilities #VU114082

Out-of-bounds read in NGINX Plus and NGINX Open Source - CVE-2025-53859

Published: August 14, 2025


Vulnerability identifier: #VU114082
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-53859
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to a boundary condition in the ngx_mail_smtp_module. A remote attacker can force the server to leak arbitrary bytes sent in a request to the authentication server.

This issue happens during the NGINX SMTP authentication process and requires the attacker to make preparations against the target system to extract the leaked data. The issue affects NGINX only if (1) it is built with the ngx_mail_smtp_module, (2) the smtp_auth directive is configured with method "none," and (3) the authentication server returns the "Auth-Wait" response header.


Affected software

NGINX Plus
NGINX Open Source
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Real Time 15
Ubuntu
Server Applications Module
openSUSE Leap
openEuler
Anolis OS
EasyApache
nginx (Ubuntu package)
nginx-debuginfo
nginx
nginx-debugsource
vim-plugin-nginx
nginx-source
nginx-mod-stream
nginx-mod-mail
nginx-mod-devel
nginx-mod-http-image-filter
nginx-mod-http-perl
nginx-mod-http-xslt-filter
nginx-filesystem
nginx-all-modules
nginx-help
nginx-doc
nginx-core

How to mitigate CVE-2025-53859

Install updates from vendor's website.

NGINX Plus - addressed in versions R32 P3, R33 P3, R34 P2, R35
NGINX Open Source - update to 1.29.1
EasyApache - update to 4 25-28
nginx (Ubuntu package) - addressed in versions 1.4.6-1ubuntu3.9+esm6, 1.10.3-0ubuntu0.16.04.5+esm7, 1.14.0-0ubuntu1.11+esm2, 1.18.0-0ubuntu1.7+esm1, 1.18.0-6ubuntu14.7, 1.24.0-2ubuntu7.5, 1.26.3-2ubuntu1.2
nginx-debuginfo - addressed in versions 1.19.8-150300.3.18.1, 1.21.5-150400.3.12.1, 1.21.5-150600.10.12.1
nginx - addressed in versions 1.19.8-150300.3.18.1, 1.21.5-150400.3.12.1, 1.21.5-150600.10.12.1
nginx-debugsource - addressed in versions 1.19.8-150300.3.18.1, 1.21.5-150400.3.12.1, 1.21.5-150600.10.12.1
vim-plugin-nginx - update to 1.19.8-150300.3.18.1
nginx-source - addressed in versions 1.19.8-150300.3.18.1, 1.21.5-150400.3.12.1, 1.21.5-150600.10.12.1
nginx-mod-stream - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-mod-mail - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-debuginfo - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-debugsource - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-mod-devel - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-mod-http-image-filter - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-mod-http-perl - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-mod-http-xslt-filter - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-filesystem - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-all-modules - addressed in versions 1.21.5-8, 1.21.5-10, 1.24.0-6
nginx-help - addressed in versions 1.21.5-10, 1.24.0-6
nginx-all-modules - update to 1.26.2-3
nginx-filesystem - update to 1.26.2-3
nginx-doc - update to 1.26.2-3
nginx-mod-stream - update to 1.26.2-3
nginx-mod-mail - update to 1.26.2-3
nginx-mod-http-xslt-filter - update to 1.26.2-3
nginx-mod-http-perl - update to 1.26.2-3
nginx-mod-http-image-filter - update to 1.26.2-3
nginx-mod-devel - update to 1.26.2-3
nginx-core - update to 1.26.2-3
nginx - update to 1.26.2-3

External References

Related Security Bulletins