CVE-2026-28753

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server.

Security Fix(es):

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-27651)

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might allow an attacker to trigger a buffer overflow to the NGINX worker process; this vulnerability may result in termination of the NGINX worker process or modification of source or destination file names outside the document root. This issue affects NGINX Open Source and NGINX Plus when the configuration file uses DAV module MOVE or COPY methods, prefix location (nonregular expression location configuration), and alias directives. The integrity impact is constrained because the NGINX worker process user has low privileges and does not have access to the entire system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-27654)

The 32-bit implementation of NGINX Open Source has a vulnerability in the ngx_http_mp4_module module, which might allow an attacker to over-read or over-write NGINX worker memory resulting in its termination, using a specially crafted MP4 file. The issue only affects 32-bit NGINX Open Source if it is built with the ngx_http_mp4_module module and the mp4 directive is used in the configuration file. Additionally, the attack is possible only if an attacker can trigger the processing of a specially crafted MP4 file with the ngx_http_mp4_module module.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-27784)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-28753)

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_mp4_module module, which might allow an attacker to trigger a buffer over-read or over-write to the NGINX worker memory resulting in its termination or possibly code execution, using a specially crafted MP4 file. This issue affects NGINX Open Source and NGINX Plus if it is built with the ngx_http_mp4_module module and the mp4 directive is used in the configuration file. Additionally, the attack is possible only if an attacker can trigger the processing of a specially crafted MP4 file with the ngx_http_mp4_module module.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-32647)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• CVE-2025-53859: fix buffer over-read in the SMTP authentication path that could disclose worker process memory to the authentication server
• CVE-2026-28753: validate host names resolved from the client address to prevent header injection into auth_http and XCLIENT requests
• CVE-2026-40701: fix use-after-free by cancelling a pending OCSP responder resolve when the client connection is closed
• CVE-2026-42934: fix buffer over-read in the charset filter when a UTF-8 sequence is split across several buffers
• CVE-2026-48142: fix remaining buffer over-read in the charset filter on invalid UTF-8 sequences
• CVE-2026-42946: reset the parsing state and restore the buffer position after an unrecognized upstream status line in the scgi and uwsgi modules

• CVE-2026-40701: fix resolver use-after-free in OCSP; the resolve context was leaked when a client SSL connection was terminated while resolving an OCSP responder, so completion of the resolve touched freed memory
• CVE-2025-53859: fix buffer over-read in ngx_mail_smtp_module; login and password storage could be left in an inconsistent state after base64 decoding errors in the plain/login/cram-md5 auth methods
• CVE-2026-28753: validate the host name resolved from the client address against the character set of RFC 1034 section 3.5, preventing CRLF injection into auth_http and smtp proxy requests
• CVE-2026-42934: fix buffer over-read in ngx_http_charset_module recode_from_utf8(); pass the saved byte count rather than the last saved index to ngx_utf8_decode() and advance past the whole saved sequence on invalid UTF-8

Buffer overflow in ngx_http_dav_module (CVE-2026-27654) Buffer overflow in the ngx_http_mp4_module (CVE-2026-27784) Buffer overflow in the ngx_http_mp4_module (CVE-2026-32647) NULL pointer dereference while using CRAM-MD5 or APOP (CVE-2026-27651) Injection in auth_http and XCLIENT (CVE-2026-28753) OCSP result bypass in stream (CVE-2026-28755)

These are all security issues fixed in the nginx-1.29.7-1.1 package on the GA media of openSUSE Tumbleweed.

This update for nginx fixes the following issues:

• CVE-2026-1642: plain text data injection into the response from an upstream proxied server (bsc#1257675).
• CVE-2026-27654: buffer overflow in the NGINX worker process via the ngx_http_dav_module module (bsc#1260416).
• CVE-2026-27784: NGINX worker memory over-read or over-write via a specially crafted MP4 file (bsc#1260417).
• CVE-2026-28753: improper handling onf CRLF sequences in CRLF responses allows for arbitrary header injection into SMTP upstream requests (bsc#1260418).
• CVE-2026-28755: TLS handshakes can succeed with revoked certificates due to improper handling of such certificates by the ngx_stream_ssl_module module (bsc#1260419).

This update for nginx fixes the following issues:

• CVE-2026-1642: plain text data injection into the response from an upstream proxied server via MITM attack (bsc#1257675).
• CVE-2026-27654: buffer overflow in the NGINX worker process via the ngx_http_dav_module module (bsc#1260416).
• CVE-2026-27784: NGINX worker memory overread or overwrite via a specially crafted MP4 file (bsc#1260417).
• CVE-2026-28753: arbitrary header injection into SMTP upstream requests via attacker-controlled DNS server (bsc#1260418).

This update for nginx fixes the following issues

Security issues:

• CVE-2026-1642: plain text data injection into the response from an upstream proxied server (bsc#1257675).
• CVE-2026-27654: buffer overflow in the NGINX worker process via the ngx_http_dav_module module (bsc#1260416).
• CVE-2026-27784: NGINX worker memory over-read or over-write via a specially crafted MP4 file (bsc#1260417).
• CVE-2026-28753: improper handling onf CRLF sequences in DNS responses allows for arbitrary header injection into SMTP upstream requests (bsc#1260418).

Non security issue:

• nginx always runs into 'timed out. Killing' on shutdown when there are long-running processes (bsc#1243502).

This update for nginx fixes the following issues:

• CVE-2026-1642: plain text data injection into the response from an upstream proxied server (bsc#1257675).
• CVE-2026-27654: buffer overflow in the NGINX worker process via the ngx_http_dav_module module (bsc#1260416).
• CVE-2026-27784: NGINX worker memory over-read or over-write via a specially crafted MP4 file (bsc#1260417).
• CVE-2026-28753: improper handling onf CRLF sequences in CRLF responses allows for arbitrary header injection into SMTP upstream requests (bsc#1260418).
• CVE-2026-28755: TLS handshakes can succeed with revoked certificates due to improper handling of such certificates by the ngx_stream_ssl_module module (bsc#1260419).