CVE-2025-53859
Last modified
CVE-2025-53859 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. 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. EPSS estimates a 0.37% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| F5 | Nginx Plus | r30 |
| F5 | Nginx Plus | r31 |
| F5 | Nginx Plus | r32 |
| F5 | Nginx Plus | r33 |
| F5 | Nginx Plus | r34 |
| F5 | Nginx Open Source | >= 0.7.22, < 1.29.1 |
References
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2025-53859?
How severe is CVE-2025-53859?
How do I fix CVE-2025-53859?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2025
- CVE-2025-53853A heap-based buffer overflow vulnerability exists in the ISH…9.8
- CVE-2025-53854A reflected cross-site scripting (xss) vulnerability exists …5.4
- CVE-2025-53855An out-of-bounds write vulnerability exists in the XML parse…7.8
- CVE-2025-53856When a virtual server, network address translation (NAT) obj…8.7
- CVE-2025-53857Mattermost Confluence Plugin version <1.5.0 fails to check t…3.7
- CVE-2025-53858ChatLuck contains a cross-site scripting vulnerability in Ch…5.4
- CVE-2025-5386A vulnerability was found in JeeWMS up to 20250504. It has b…9.8
- CVE-2025-53860A vulnerability exists in F5OS-A software that allows a high…4.1
- CVE-2025-53861A flaw was found in Ansible. Sensitive cookies without secur…3.1
- CVE-2025-53862A flaw was found in Ansible. Three API endpoints are accessi…3.5
- CVE-2025-53864Connect2id Nimbus JOSE + JWT 10.0.x before 10.0.2 and 9.37.x…5.8
- CVE-2025-53865In Roundup before 2.5.0, XSS can occur via interaction betwe…6.4
Are you affected by CVE-2025-53859?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST