CVE-2019-14495 (published 2019-08-01T17:15Z)

webadmin.c in 3proxy before 0.8.13 has an out-of-bounds write in the admin interface.

Severity: HIGH
CVSS v2 base score: 7.5 (AV:N/AC:L/Au:N/C:P/I:P/A:P)
CVSS v3 base score: 9.8, CRITICAL (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-787
cwe_name: Out-of-bounds Write
description: The product writes data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/z3APA3A/3proxy
commit_details: repo_url: https://github.com/z3APA3A/3proxy
author: z3APA3A
author_date: 2019-08-01 16:46:22+03:00
msg: Fix: out-of-bounds write and few more bugs in 'admin' configuration upload
repository: repo_url: https://github.com/z3APA3A/3proxy
repo_name: 3proxy/3proxy
description: 3proxy - tiny free proxy server
repo_language: C
owner: z3APA3A
file_changes: filename: webadmin.c
change_type: ModificationType.MODIFY
diff: @@ -10,7 +10,7 @@
 
 #define RETURN(xxx) { param->res = xxx; goto CLEANRET; }
 
-#define LINESIZE 2048
+#define LINESIZE 65536
 
 extern FILE *writable;
 FILE * confopen();
@@ -341,7 +341,7 @@ void * adminchild(struct clientparam* param) {
  char *sb;
  char *req = NULL;
  struct printparam pp;
- int contentlen = 0;
+ unsigned contentlen = 0;
  int isform = 0;
 
  pp.inbuf = 0;
@@ -390,7 +390,8 @@ void * adminchild(struct clientparam* param) {
 	else if(i > 15 && (!strncasecmp(buf, "content-length:", 15))){
 		sb = buf + 15;
 		while(isspace(*sb))sb++;
-		contentlen = atoi(sb);
+		sscanf(sb, "%u", &contentlen);
+		if(contentlen > LINESIZE*1024) contentlen = 0;
 	}
 	else if(i > 13 && (!strncasecmp(buf, "content-type:", 13))){
 		sb = buf + 13;
@@ -520,7 +521,7 @@ void * adminchild(struct clientparam* param) {
 				break;
 			}
 				printstr(&pp, "<h3>Please be careful editing config file remotely</h3>");
-				printstr(&pp, "<form method=\"POST\" action=\"/U\"><textarea cols=\"80\" rows=\"30\" name=\"conffile\">");
+				printstr(&pp, "<form method=\"POST\" action=\"/U\" enctype=\"application/x-www-form-urlencoded\"><textarea cols=\"80\" rows=\"30\" name=\"conffile\">");
 				while(fgets(buf, 256, fp)){
 					printstr(&pp, buf);
 				}
@@ -530,24 +531,23 @@ void * adminchild(struct clientparam* param) {
 		}
 	case 'U':
 		{
-			int l=0;
+			unsigned l=0;
 			int error = 0;
 
-			if(!writable || fseek(writable, 0, 0)){
+			if(!writable || !contentlen || fseek(writable, 0, 0)){
 				error = 1;
 			}
-			while((i = sockgetlinebuf(param, CLIENT, (unsigned char *)buf, LINESIZE - 1, '+', conf.timeouts[STRING_S])) > 0){
+			while(l < contentlen && (i = sockgetlinebuf(param, CLIENT, (unsigned char *)buf, (contentlen - l) > LINESIZE - 1?LINESIZE - 1:contentlen - l, '+', conf.timeouts[STRING_S])) > 0){
 				if(i > (contentlen - l)) i = (contentlen - l);
-				buf[i] = 0;
 				if(!l){
-					if(strncasecmp(buf, "conffile=", 9)) error = 1;
+					if(i<9 || strncasecmp(buf, "conffile=", 9)) error = 1;
 				}
 				if(!error){
+					buf[i] = 0;
 					decodeurl((unsigned char *)buf, 1);
 					fprintf(writable, "%s", l? buf : buf + 9);
 				}
 				l += i;
-				if(l >= contentlen) break;
 			}
 			if(writable && !error){
 				fflush(writable);

programming_language: C