Fix CVE-2026-42945 Buffer overrun in rewrite module via arguments in replacement strings

SOURCES/0014-Rewrite-fixed-escaping-and-possible-buffer-overrun.patch

@@ -0,0 +1,42 @@
+From 524977e7c534e87e5b55739fa74601c9f1102686 Mon Sep 17 00:00:00 2001
+From: Roman Arutyunyan <arut@nginx.com>
+Date: Wed, 22 Apr 2026 09:39:31 +0400
+Subject: [PATCH] Rewrite: fixed escaping and possible buffer overrun
+
+The following code resulted in incorrect escaping of $1 and possible
+segfault:
+
+    location / {
+        rewrite ^(.*) /new?c=1;
+        set $myvar $1;
+        return 200 $myvar;
+    }
+
+If there were arguments in a rewrite's replacement string, the is_args flag
+was set and incorrectly never cleared.  This resulted in escaping applied
+to any captures evaluated afterwards in set or if.  Additionally buffer was
+allocated by ngx_http_script_complex_value_code() without escaping expected,
+thus this also resulted in buffer overrun and possible segfault.
+
+A similar issue was fixed in 74d939974d43.
+
+Reported by Leo Lin.
+---
+ src/http/ngx_http_script.c | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/src/http/ngx_http_script.c b/src/http/ngx_http_script.c
+index a2b9f1b7bf..2ea6113735 100644
+--- a/src/http/ngx_http_script.c
++++ b/src/http/ngx_http_script.c
+@@ -1202,6 +1202,7 @@ ngx_http_script_regex_end_code(ngx_http_script_engine_t *e)
+
+     r = e->request;
+
++    e->is_args = 0;
+     e->quote = 0;
+
+     ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+--
+2.53.0
+

SPECS/nginx.spec

@@ -67,7 +67,7 @@
 Name:              nginx
 Epoch:             2
 Version:           1.26.3
-Release:           2%{?dist}.1
+Release:           2%{?dist}.1.alma.1
 
 Summary:           A high performance web server and reverse proxy server
 License:           BSD-2-Clause
@@ -144,6 +144,10 @@ Patch11:           0012-Mail-fixed-clearing-s-passwd-in-auth-http-requests.patch
 # upstream patch - https://github.com/nginx/nginx/commit/7725c372c2f
 Patch12:           0013-Mp4-avoid-zero-size-buffers-in-output.patch
 
+# CVE-2026-42945
+# upstream patch - https://github.com/nginx/nginx/commit/524977e7c534e87e5b55739fa74601c9f1102686
+Patch13:           0014-Rewrite-fixed-escaping-and-possible-buffer-overrun.patch
+
 
 BuildRequires:     make
 BuildRequires:     gcc
@@ -666,6 +670,10 @@ fi
 
 %changelog
 ## START: Generated by rpmautospec
+* Thu May 14 2026 Jonathan Wright <jonathan@almalinux.org> - 2:1.26.3-2.1.alma.1
+- Fix CVE-2026-42945 nginx: NGINX: Buffer overrun in rewrite module via
+  arguments in replacement strings
+
 * Wed Apr 01 2026 Zdenek Dohnal <zdohnal@redhat.com> - 2:1.26.3-6
 - Resolves: RHEL-157887 - CVE-2026-32647 nginx:1.26/nginx: NGINX: Denial of
   Service or Code Execution via specially crafted MP4 files