nginx: fix CVE-2026-28753

As per the advisory[1] mentioned in NVD[2], version 1.28.3 contains the fix.
Backport the commit[3] from 1.28.3 changelog matching the description.

[1] https://my.f5.com/manage/s/article/K000160367
[2] https://nvd.nist.gov/vuln/detail/CVE-2026-28753
[3] https://github.com/nginx/nginx/commit/6a8513761fb327f67fcc6cfcf1ad216887e2589f

Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com>
Signed-off-by: Anuj Mittal <anuj.mittal@oss.qualcomm.com>

meta-webserver/recipes-httpd/nginx/nginx-1.24.0/CVE-2026-28753.patch

@@ -0,0 +1,93 @@
+From 7e705808a8568a091a8ecf418ed9f77914304fcc Mon Sep 17 00:00:00 2001
+From: Roman Arutyunyan <arut@nginx.com>
+Date: Thu, 26 Feb 2026 11:52:53 +0400
+Subject: [PATCH] Mail: host validation.
+
+Now host name resolved from client address is validated to only contain
+the characters specified in RFC 1034, Section 3.5.  The validation allows
+to avoid injections when using the resolved host name in auth_http and
+smtp proxy.
+
+Reported by Asim Viladi Oglu Manizada, Colin Warren,
+Xiao Liu (Yunnan University), Yuan Tan (UC Riverside), and
+Bird Liu (Lanzhou University).
+
+(cherry picked from commit 6a8513761fb327f67fcc6cfcf1ad216887e2589f)
+
+CVE: CVE-2026-28753
+Upstream-Status: Backport [https://github.com/nginx/nginx/commit/6a8513761fb327f67fcc6cfcf1ad216887e2589f]
+Signed-off-by: Ankur Tyagi <ankur.tyagi85@gmail.com>
+---
+ src/mail/ngx_mail_smtp_handler.c | 45 ++++++++++++++++++++++++++++++++
+ 1 file changed, 45 insertions(+)
+
+diff --git a/src/mail/ngx_mail_smtp_handler.c b/src/mail/ngx_mail_smtp_handler.c
+index e68ceedfd..e477741c8 100644
+--- a/src/mail/ngx_mail_smtp_handler.c
++++ b/src/mail/ngx_mail_smtp_handler.c
+@@ -13,6 +13,7 @@
+ 
+ 
+ static void ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx);
++static ngx_int_t ngx_mail_smtp_validate_host(ngx_str_t *name);
+ static void ngx_mail_smtp_resolve_name(ngx_event_t *rev);
+ static void ngx_mail_smtp_resolve_name_handler(ngx_resolver_ctx_t *ctx);
+ static void ngx_mail_smtp_block_reading(ngx_event_t *rev);
+@@ -127,6 +128,20 @@ ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx)
+         return;
+     }
+ 
++    if (ngx_mail_smtp_validate_host(&ctx->name) != NGX_OK) {
++        ngx_log_error(NGX_LOG_ERR, c->log, 0,
++                      "%V resolved to invalid host name \"%V\"",
++                      &c->addr_text, &ctx->name);
++
++        s->host = smtp_tempunavail;
++
++        ngx_resolve_addr_done(ctx);
++
++        ngx_mail_smtp_greeting(s, s->connection);
++
++        return;
++    }
++
+     c->log->action = "in resolving client hostname";
+ 
+     s->host.data = ngx_pstrdup(c->pool, &ctx->name);
+@@ -149,6 +164,36 @@ ngx_mail_smtp_resolve_addr_handler(ngx_resolver_ctx_t *ctx)
+ }
+ 
+ 
++static ngx_int_t
++ngx_mail_smtp_validate_host(ngx_str_t *name)
++{
++    u_char      ch;
++    ngx_uint_t  i;
++
++    if (name->len == 0) {
++        return NGX_DECLINED;
++    }
++
++    for (i = 0; i < name->len; i++) {
++        ch = name->data[i];
++
++        /* allow only characters from RFC 1034, Section 3.5 */
++
++        if ((ch >= 'a' && ch <= 'z')
++            || (ch >= 'A' && ch <= 'Z')
++            || (ch >= '0' && ch <= '9')
++            || ch == '-' || ch == '.')
++        {
++            continue;
++        }
++
++        return NGX_DECLINED;
++    }
++
++    return NGX_OK;
++}
++
++
+ static void
+ ngx_mail_smtp_resolve_name(ngx_event_t *rev)
+ {

meta-webserver/recipes-httpd/nginx/nginx_1.24.0.bb

@@ -7,6 +7,7 @@ SRC_URI:append = " \
                   file://CVE-2026-28755.patch \
                   file://CVE-2026-27651.patch \
                   file://CVE-2026-27654.patch \
+                  file://CVE-2026-28753.patch \
 "
 
 SRC_URI[sha256sum] = "77a2541637b92a621e3ee76776c8b7b40cf6d707e69ba53a940283e30ff2f55d"