From: Harry Sintonen <sintonen@iki.fi>
Date: Fri, 7 May 2021 11:09:57 +0000 (+0200)
Subject: telnet: check sscanf() for correct number of matches
X-Git-Tag: curl-7_77_0~13
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=39ce47f219b09c380b81f89fe54ac586c8db6bde;p=thirdparty%2Fcurl.git

telnet: check sscanf() for correct number of matches

CVE-2021-22898

Bug: https://curl.se/docs/CVE-2021-22898.html
---

diff --git a/lib/telnet.c b/lib/telnet.c
index 26e0658ba9..fdd137fb0c 100644
--- a/lib/telnet.c
+++ b/lib/telnet.c
@@ -922,7 +922,7 @@ static void suboption(struct Curl_easy *data)
         size_t tmplen = (strlen(v->data) + 1);
         /* Add the variable only if it fits */
         if(len + tmplen < (int)sizeof(temp)-6) {
-          if(sscanf(v->data, "%127[^,],%127s", varname, varval)) {
+          if(sscanf(v->data, "%127[^,],%127s", varname, varval) == 2) {
             msnprintf((char *)&temp[len], sizeof(temp) - len,
                       "%c%s%c%s", CURL_NEW_ENV_VAR, varname,
                       CURL_NEW_ENV_VALUE, varval);