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

SOURCES/0012-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

@@ -30,7 +30,7 @@
 Name:              nginx
 Epoch:             1
 Version:           1.24.0
-Release:           3%{?dist}.alma.1
+Release:           3%{?dist}.alma.2
 
 Summary:           A high performance web server and reverse proxy server
 Group:             System Environment/Daemons
@@ -98,6 +98,10 @@ Patch10:           0010-Mail-fixed-clearing-s-passwd-in-auth-http-requests.patch
 # upstream patch - https://github.com/nginx/nginx/commit/7725c372c2f
 Patch11:           0011-Mp4-avoid-zero-size-buffers-in-output.patch
 
+# CVE-2026-42945
+# upstream patch - https://github.com/nginx/nginx/commit/524977e7c534e87e5b55739fa74601c9f1102686
+Patch12:           0012-Rewrite-fixed-escaping-and-possible-buffer-overrun.patch
+
 %if 0%{?with_gperftools}
 BuildRequires:     gperftools-devel
 %endif
@@ -260,6 +264,7 @@ Requires:          zlib-devel
 %patch -P9 -p1
 %patch -P10 -p1
 %patch -P11 -p1
+%patch -P12 -p1
 
 cp %{SOURCE200} %{SOURCE210} %{SOURCE10} %{SOURCE12} .
 
@@ -572,6 +577,10 @@ fi
 %{nginx_srcdir}/
 
 %changelog
+* Thu May 14 2026 Jonathan Wright <jonathan@almalinux.org> - 1:1.24.0-3.alma.2
+- Fix CVE-2026-42945 nginx: NGINX: Buffer overrun in rewrite module via
+  arguments in replacement strings
+
 * Tue Apr 07 2026 Eduard Abdullin <eabdullin@almalinux.org> - 1:1.24.0-3.alma.1
 - Debrand for AlmaLinux