Bug 2388238 (CVE-2025-53859)

Summary: CVE-2025-53859 nginx: NGINX ngx_mail_smtp_module vulnerability
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: caswilli, kaycoth
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A memory access flaw has been discovered in nginx. The ngx_mail_smtp_module might allow an unauthenticated attacker to over-read NGINX SMTP authentication process memory. As a result, the server side may leak arbitrary bytes sent in a request to the authentication server. This issue occurs during the NGINX SMTP authentication process, requiring the attacker to prepare against the target system to extract the leaked data.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2388410, 2388411    
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Description OSIDB Bzimport 2025-08-13 15:01:36 UTC 
NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_module that might allow an unauthenticated attacker to over-read NGINX SMTP authentication process memory; as a result, the server side may 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.




Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.