diff --git a/docs/manual/rewrite/flags.html.en b/docs/manual/rewrite/flags.html.en

index 80d0759..9673094 100644

--- a/docs/manual/rewrite/flags.html.en

+++ b/docs/manual/rewrite/flags.html.en

@@ -85,10 +85,6 @@ of how you might use them.

 
B (escape backreferences)

 
The [B] flag instructs RewriteRule to escape non-alphanumeric

 characters before applying the transformation.

-
In 2.4.26 and later, you can limit the escaping to specific characters

-in backreferences by listing them: [B=#?;]. Note: The space

-character can be used in the list of characters to escape, but it cannot be

-the last character in the list.

 
mod_rewrite has to unescape URLs before mapping them,

 so backreferences are unescaped at the time they are applied.

@@ -120,6 +116,16 @@ when the backend may break if presented with an unescaped URL.

 
An alternative to this flag is using a RewriteCond to capture against %{THE_REQUEST} which will capture

 strings in the encoded form.

+

+
In 2.4.26 and later, you can limit the escaping to specific characters

+in backreferences by listing them: [B=#?;]. Note: The space

+character can be used in the list of characters to escape, but you must quote

+the entire third argument of RewriteRule

+and the space must not be the last character in the list.

+

+
# Escape spaces and question marks.

+RewriteRule "^search/(.*)$" "/search.php?term=$1" "[B= ?]"

+

 
BNP|backrefnoplus (don't escape space to +)

diff --git a/modules/http2/mod_proxy_http2.c b/modules/http2/mod_proxy_http2.c

index a7e0dcd..9aa1f89 100644

--- a/modules/http2/mod_proxy_http2.c

+++ b/modules/http2/mod_proxy_http2.c

@@ -178,6 +178,16 @@ static int proxy_http2_canon(request_rec *r, char *url)

             path = ap_proxy_canonenc(r->pool, url, (int)strlen(url),

                                      enc_path, 0, r->proxyreq);

             search = r->args;

+            if (search && *(ap_scan_vchar_obstext(search))) {

+                /*

+                 * We have a raw control character or a ' ' in r->args.

+                 * Correct encoding was missed.

+                 */

+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10412)

+                              "To be forwarded query string contains control "

+                              "characters or spaces");

+                return HTTP_FORBIDDEN;

+            }

         }

         break;

     case PROXYREQ_PROXY:

diff --git a/modules/mappers/mod_rewrite.c b/modules/mappers/mod_rewrite.c

index 38dbb24..7e2b452 100644

--- a/modules/mappers/mod_rewrite.c

+++ b/modules/mappers/mod_rewrite.c

@@ -168,6 +168,7 @@ static const char* really_last_key = "rewrite_really_last";

 #define RULEFLAG_END                (1<<17)

 #define RULEFLAG_ESCAPENOPLUS       (1<<18)

 #define RULEFLAG_QSLAST             (1<<19)

+#define RULEFLAG_QSNONE             (1<<20) /* programattic only */

 /* return code of the rewrite rule

  * the result may be escaped - or not

@@ -761,15 +762,24 @@ static char *escape_absolute_uri(apr_pool_t *p, char *uri, unsigned scheme)

                        ap_escape_uri(p, cp), NULL);

 }

+

 /*

  * split out a QUERY_STRING part from

  * the current URI string

  */

-static void splitout_queryargs(request_rec *r, int qsappend, int qsdiscard, 

-                               int qslast)

+static void splitout_queryargs(request_rec *r, int flags)

 {

     char *q;

     int split;

+    int qsappend = flags & RULEFLAG_QSAPPEND;

+    int qsdiscard = flags & RULEFLAG_QSDISCARD;

+    int qslast = flags & RULEFLAG_QSLAST;

+

+    if (flags & RULEFLAG_QSNONE) {

+        rewritelog((r, 2, NULL, "discarding query string, no parse from substitution"));

+        r->args = NULL;

+        return;

+    }

     /* don't touch, unless it's a scheme for which a query string makes sense.

      * See RFC 1738 and RFC 2368.

@@ -794,7 +804,7 @@ static void splitout_queryargs(request_rec *r, int qsappend, int qsdiscard,

         olduri = apr_pstrdup(r->pool, r->filename);

         *q++ = '\0';

         if (qsappend) {

-            if (*q) { 

+            if (*q) {

                 r->args = apr_pstrcat(r->pool, q, "&" , r->args, NULL);

             }

         }

@@ -802,9 +812,9 @@ static void splitout_queryargs(request_rec *r, int qsappend, int qsdiscard,

             r->args = apr_pstrdup(r->pool, q);

         }

-        if (r->args) { 

+        if (r->args) {

            len = strlen(r->args);

-      

+

            if (!len) {

                r->args = NULL;

            }

@@ -2733,7 +2743,7 @@ static apr_status_t rewritelock_remove(void *data)

  * XXX: what an inclined parser. Seems we have to leave it so

  *      for backwards compat. *sigh*

  */

-static int parseargline(char *str, char **a1, char **a2, char **a3)

+static int parseargline(char *str, char **a1, char **a2, char **a2_end, char **a3)

 {

     char quote;

@@ -2784,8 +2794,10 @@ static int parseargline(char *str, char **a1, char **a2, char **a3)

     if (!*str) {

         *a3 = NULL; /* 3rd argument is optional */

+        *a2_end = str;

         return 0;

     }

+    *a2_end = str;

     *str++ = '\0';

     while (apr_isspace(*str)) {

@@ -3323,7 +3335,7 @@ static const char *cmd_rewritecond(cmd_parms *cmd, void *in_dconf,

     rewrite_server_conf *sconf;

     rewritecond_entry *newcond;

     ap_regex_t *regexp;

-    char *a1 = NULL, *a2 = NULL, *a3 = NULL;

+    char *a1 = NULL, *a2 = NULL, *a2_end, *a3 = NULL;

     const char *err;

     sconf = ap_get_module_config(cmd->server->module_config, &rewrite_module);

@@ -3341,7 +3353,7 @@ static const char *cmd_rewritecond(cmd_parms *cmd, void *in_dconf,

      * of the argument line. So we can use a1 .. a3 without

      * copying them again.

      */

-    if (parseargline(str, &a1, &a2, &a3)) {

+    if (parseargline(str, &a1, &a2, &a2_end, &a3)) {

         return apr_pstrcat(cmd->pool, "RewriteCond: bad argument line '", str,

                            "'", NULL);

     }

@@ -3749,7 +3761,7 @@ static const char *cmd_rewriterule(cmd_parms *cmd, void *in_dconf,

     rewrite_server_conf *sconf;

     rewriterule_entry *newrule;

     ap_regex_t *regexp;

-    char *a1 = NULL, *a2 = NULL, *a3 = NULL;

+    char *a1 = NULL, *a2 = NULL, *a2_end, *a3 = NULL;

     const char *err;

     sconf = ap_get_module_config(cmd->server->module_config, &rewrite_module);

@@ -3763,7 +3775,7 @@ static const char *cmd_rewriterule(cmd_parms *cmd, void *in_dconf,

     }

     /*  parse the argument line ourself */

-    if (parseargline(str, &a1, &a2, &a3)) {

+    if (parseargline(str, &a1, &a2, &a2_end, &a3)) {

         return apr_pstrcat(cmd->pool, "RewriteRule: bad argument line '", str,

                            "'", NULL);

     }

@@ -3810,6 +3822,17 @@ static const char *cmd_rewriterule(cmd_parms *cmd, void *in_dconf,

         newrule->flags |= RULEFLAG_NOSUB;

     }

+    if (*(a2_end-1) == '?') {

+        /* a literal ? at the end of the unsubstituted rewrite rule */

+        newrule->flags |= RULEFLAG_QSNONE;

+        *(a2_end-1) = '\0'; /* trailing ? has done its job */

+    }

+    else if (newrule->flags & RULEFLAG_QSDISCARD) {

+        if (NULL == ap_strchr(newrule->output, '?')) {

+            newrule->flags |= RULEFLAG_QSNONE;

+        }

+    }

+

     /* now, if the server or per-dir config holds an

      * array of RewriteCond entries, we take it for us

      * and clear the array

@@ -4215,9 +4238,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)

         r->path_info = NULL;

     }

-    splitout_queryargs(r, p->flags & RULEFLAG_QSAPPEND, 

-                          p->flags & RULEFLAG_QSDISCARD, 

-                          p->flags & RULEFLAG_QSLAST);

+    splitout_queryargs(r, p->flags);

     /* Add the previously stripped per-directory location prefix, unless

      * (1) it's an absolute URL path and

@@ -4699,6 +4720,17 @@ static int hook_uri2file(request_rec *r)

         unsigned skip;

         apr_size_t flen;

+        if (r->args && *(ap_scan_vchar_obstext(r->args))) {

+            /*

+             * We have a raw control character or a ' ' in r->args.

+             * Correct encoding was missed.

+             */

+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10410)

+                          "Rewritten query string contains control "

+                          "characters or spaces");

+            return HTTP_FORBIDDEN;

+        }

+

         if (ACTION_STATUS == rulestatus) {

             int n = r->status;

@@ -4983,6 +5015,17 @@ static int hook_fixup(request_rec *r)

     if (rulestatus) {

         unsigned skip;

+        if (r->args && *(ap_scan_vchar_obstext(r->args))) {

+            /*

+             * We have a raw control character or a ' ' in r->args.

+             * Correct encoding was missed.

+             */

+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10411)

+                          "Rewritten query string contains control "

+                          "characters or spaces");

+            return HTTP_FORBIDDEN;

+        }

+

         if (ACTION_STATUS == rulestatus) {

             int n = r->status;

diff --git a/modules/proxy/mod_proxy_ajp.c b/modules/proxy/mod_proxy_ajp.c

index eb550e5..8b8d09e 100644

--- a/modules/proxy/mod_proxy_ajp.c

+++ b/modules/proxy/mod_proxy_ajp.c

@@ -69,6 +69,16 @@ static int proxy_ajp_canon(request_rec *r, char *url)

         path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,

                                  r->proxyreq);

         search = r->args;

+        if (search && *(ap_scan_vchar_obstext(search))) {

+            /*

+             * We have a raw control character or a ' ' in r->args.

+             * Correct encoding was missed.

+             */

+             ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10406)

+                           "To be forwarded query string contains control "

+                           "characters or spaces");

+             return HTTP_FORBIDDEN;

+        }

     }

     if (path == NULL)

         return HTTP_BAD_REQUEST;

diff --git a/modules/proxy/mod_proxy_balancer.c b/modules/proxy/mod_proxy_balancer.c

index c6c7e89..9a5cb08 100644

--- a/modules/proxy/mod_proxy_balancer.c

+++ b/modules/proxy/mod_proxy_balancer.c

@@ -106,6 +106,16 @@ static int proxy_balancer_canon(request_rec *r, char *url)

         path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,

                                  r->proxyreq);

         search = r->args;

+        if (search && *(ap_scan_vchar_obstext(search))) {

+            /*

+             * We have a raw control character or a ' ' in r->args.

+             * Correct encoding was missed.

+             */

+             ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10407)

+                           "To be forwarded query string contains control "

+                           "characters or spaces");

+             return HTTP_FORBIDDEN;

+        }

     }

     if (path == NULL)

         return HTTP_BAD_REQUEST;

diff --git a/modules/proxy/mod_proxy_http.c b/modules/proxy/mod_proxy_http.c

index a33b57b..f528d94 100644

--- a/modules/proxy/mod_proxy_http.c

+++ b/modules/proxy/mod_proxy_http.c

@@ -90,6 +90,16 @@ static int proxy_http_canon(request_rec *r, char *url)

             path = ap_proxy_canonenc(r->pool, url, strlen(url),

                                      enc_path, 0, r->proxyreq);

             search = r->args;

+            if (search && *(ap_scan_vchar_obstext(search))) {

+                /*

+                 * We have a raw control character or a ' ' in r->args.

+                 * Correct encoding was missed.

+                 */

+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10408)

+                              "To be forwarded query string contains control "

+                              "characters or spaces");

+                return HTTP_FORBIDDEN;

+            }

         }

         break;

     case PROXYREQ_PROXY:

diff --git a/modules/proxy/mod_proxy_wstunnel.c b/modules/proxy/mod_proxy_wstunnel.c

index 9dda010..05f5d1e 100644

--- a/modules/proxy/mod_proxy_wstunnel.c

+++ b/modules/proxy/mod_proxy_wstunnel.c

@@ -73,6 +73,16 @@ static int proxy_wstunnel_canon(request_rec *r, char *url)

         path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,

                                  r->proxyreq);

         search = r->args;

+        if (search && *(ap_scan_vchar_obstext(search))) {

+            /*

+             * We have a raw control character or a ' ' in r->args.

+             * Correct encoding was missed.

+             */

+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10409)

+                          "To be forwarded query string contains control "

+                          "characters or spaces");

+            return HTTP_FORBIDDEN;

+        }

     }

     if (path == NULL)

         return HTTP_BAD_REQUEST;