From ca6d87680b10199c710b47d24c3ceabf13201a51 Mon Sep 17 00:00:00 2001 From: Daniel Stenberg Date: Mon, 6 Mar 2023 12:07:33 +0100 Subject: [PATCH] [PATCH] telnet: only accept option arguments in ascii To avoid embedded telnet negotiation commands etc. Reported-by: Harry Sintonen Closes #10728 Backported to Debian by Samuel Henrique Gbp-Pq: Name CVE-2023-27533.patch --- lib/telnet.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/lib/telnet.c b/lib/telnet.c index a964bfdc..18e739bb 100644 --- a/lib/telnet.c +++ b/lib/telnet.c @@ -770,6 +770,17 @@ static void printsub(struct Curl_easy *data, } } +static bool str_is_nonascii(const char *str) +{ + size_t len = strlen(str); + while(len--) { + if(*str & 0x80) + return TRUE; + str++; + } + return FALSE; +} + static CURLcode check_telnet_options(struct Curl_easy *data) { struct curl_slist *head; @@ -784,6 +795,8 @@ static CURLcode check_telnet_options(struct Curl_easy *data) /* Add the user name as an environment variable if it was given on the command line */ if(data->state.aptr.user) { + if(str_is_nonascii(data->conn->user)) + return CURLE_BAD_FUNCTION_ARGUMENT; msnprintf(option_arg, sizeof(option_arg), "USER,%s", conn->user); beg = curl_slist_append(tn->telnet_vars, option_arg); if(!beg) { @@ -798,7 +811,8 @@ static CURLcode check_telnet_options(struct Curl_easy *data) for(head = data->set.telnet_options; head; head = head->next) { if(sscanf(head->data, "%127[^= ]%*[ =]%255s", option_keyword, option_arg) == 2) { - + if(str_is_nonascii(option_arg)) + continue; /* Terminal type */ if(strcasecompare(option_keyword, "TTYPE")) { strncpy(tn->subopt_ttype, option_arg, 31); -- 2.30.2