CVE-2025-53859
published 2025-08-13CVE-2025-53859: 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…
PriorityP422low3.7CVSS 3.1
AVNACHPRNUINSUCLINAN
EPSS
0.39%
31.7th percentile
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.
Affected
27 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | nginx | < nginx 1.22.1-9+deb12u3 (bookworm) | nginx 1.22.1-9+deb12u3 (bookworm) |
| f5 | nginx | >= 0 < 1.28.2-r0 | 1.28.2-r0 |
| f5 | nginx | >= 0 < 1.28.2-r0 | 1.28.2-r0 |
| f5 | nginx | >= 0 < 1.22.1-9+deb12u3 | 1.22.1-9+deb12u3 |
| f5 | nginx | >= 0 < 1.26.3-3+deb13u1 | 1.26.3-3+deb13u1 |
| f5 | nginx | >= 0 < 1.28.0-3 | 1.28.0-3 |
| f5 | nginx_open_source | — | — |
| f5 | nginx_open_source | >= 0.7 < 1.29.1 | 1.29.1 |
| f5 | nginx_open_source | >= 0.7.22 < 1.29.1 | 1.29.1 |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | — | — |
| f5 | nginx_plus | >= R30 < * | * |
| f5 | nginx_plus | >= R31 < * | * |
| f5 | nginx_plus | >= R32 < R32 P3 | R32 P3 |
| f5 | nginx_plus | >= R33 < R33 P3 | R33 P3 |
| f5 | nginx_plus | >= R34 < R34 P2 | R34 P2 |
| msrc | azl3_gh_2.62.0-1_on_azure_linux_3.0 | — | — |
| msrc | azl3_gh_2.62.0-8_on_azure_linux_3.0 | — | — |
| msrc | azl3_nginx_1.25.4-4_on_azure_linux_3.0 | — | — |
| msrc | azl3_nginx_1.25.4-5_on_azure_linux_3.0 | — | — |
| msrc | cbl2_nginx_1.22.1-13_on_cbl_mariner_2.0 | — | — |
CVSS provenance
nvdv3.13.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
nvdv4.06.3MEDIUMCVSS: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
osv6.3MEDIUM
vendor_msrc6.5MEDIUM
vendor_debian6.3MEDIUM
vendor_redhat6.3MEDIUM
vendor_ubuntu6.3MEDIUM
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Ubuntu
nginx vulnerabilities
vendor_ubuntu·2026-06-03·CVSS 6.3
CVE-2026-1642 [MEDIUM] nginx vulnerabilities
Title: nginx vulnerabilities
Summary: Several security issues were fixed in nginx.
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
Ubuntu
nginx vulnerability
vendor_ubuntu·2025-08-25
CVE-2025-53859 nginx vulnerability
Title: nginx vulnerability
Summary: nginx could be made to expose sensitive information over the
network.
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.
Instructions: In general, a standard system update will make all the necessary changes.
Red Hat
nginx: NGINX ngx_mail_smtp_module vulnerability
vendor_redhat·2025-08-13·CVSS 6.3
CVE-2025-53859 [MEDIUM] CWE-125 nginx: NGINX ngx_mail_smtp_module vulnerability
nginx: NGINX ngx_mail_smtp_module vulnerability
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 eva
F5
CVE-2025-53859: NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_module that might allow an unauthenticated...
vendor_f5·2025-08-13·CVSS 3.7
CVE-2025-53859 [MEDIUM] CWE-125 CVE-2025-53859: NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_module that might allow an unauthenticated...
CVE-2025-53859: NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_module that might allow an unauthenticated...
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 heade
Microsoft
NGINX ngx_mail_smtp_module vulnerability
vendor_msrc·2025-08-12·CVSS 5.6
CVE-2025-53859 [MEDIUM] CWE-125 NGINX ngx_mail_smtp_module vulnerability
NGINX ngx_mail_smtp_module vulnerability
FAQ: Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Mariner: Mariner
f5: f5
Customer Action Required: Yes
Remediation: CBL-Mariner Releases
Reference: https://learn.microsoft.com/en-us/
Debian
CVE-2025-53859: nginx - NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_modul...
vendor_debian·2025·CVSS 6.3
CVE-2025-53859 [MEDIUM] CVE-2025-53859: nginx - NGINX Open Source and NGINX Plus have a vulnerability in the ngx_mail_smtp_modul...
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.
Scope: local
bookworm: resolved (fixed in
Microsoft
go-gh `auth.TokenForHost` violates GitHub host security boundary within a codespace
vendor_msrc·2024-11-12·CVSS 6.5
CVE-2024-53859 [MEDIUM] CWE-200 go-gh `auth.TokenForHost` violates GitHub host security boundary within a codespace
go-gh `auth.TokenForHost` violates GitHub host security boundary within a codespace
FAQ: Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Mariner: Mariner
GitHub_M: GitHub_M
Customer Action Required: Yes
Remediation: CBL-Mariner
OSV
CVE-2025-53859: 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
osv·2025-08-13·CVSS 6.3
CVE-2025-53859 [MEDIUM] CVE-2025-53859: 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
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.
GHSA
GHSA-2qmj-q2xc-85v8: 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
ghsa_unreviewed·2025-08-13
CVE-2025-53859 [MEDIUM] CWE-125 GHSA-2qmj-q2xc-85v8: 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
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.
OSV
CVE-2025-53859: 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
osv·2025-08-13·CVSS 6.3
CVE-2025-53859 [MEDIUM] CVE-2025-53859: 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
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2025-08-13
Published