Arch Linux Security Advisory ASA-201710-4 ========================================= Severity: Medium Date : 2017-10-05 CVE-ID : CVE-2017-1000099 CVE-2017-1000100 CVE-2017-1000254 Package : lib32-libcurl-gnutls Type : multiple issues Remote : Yes Link : https://security.archlinux.org/AVG-386 Summary ======= The package lib32-libcurl-gnutls before version 7.56.0-1 is vulnerable to multiple issues including information disclosure and denial of service. Resolution ========== Upgrade to 7.56.0-1. # pacman -Syu "lib32-libcurl-gnutls>=7.56.0-1" The problems have been fixed upstream in version 7.56.0. Workaround ========== None. Description =========== - CVE-2017-1000099 (information disclosure) An information disclosure issue has been found in curl < 7.55.0. When asking to get a file from a file:// URL, libcurl provides a feature that outputs meta-data about the file using HTTP-like headers. The code doing this would send the wrong buffer to the user (stdout or the application's provide callback), which could lead to other private data from the heap to get inadvertently displayed. The wrong buffer was an uninitialized memory area allocated on the heap and if it turned out to not contain any zero byte, it would continue and display the data following that buffer in memory. - CVE-2017-1000100 (information disclosure) An information disclosure issue has been found in curl < 7.55.0. When doing a TFTP transfer and curl/libcurl is given a URL that contains a very long file name (longer than about 515 bytes), the file name is truncated to fit within the buffer boundaries, but the buffer size is still wrongly updated to use the untruncated length. This too large value is then used in the sendto() call, making curl attempt to send more data than what is actually put into the buffer. The sendto() function will then read beyond the end of the heap based buffer. A malicious HTTP(S) server could redirect a vulnerable libcurl-using client to a crafted TFTP URL (if the client hasn't restricted which protocols it allows redirects to) and trick it to send private memory contents to a remote server over UDP. - CVE-2017-1000254 (denial of service) When libcurl connects to an FTP server and successfully logs in (anonymous or not), it asks the server for the current directory with the `PWD` command. The server then responds with a 257 response containing the path, inside double quotes. The returned path name is then kept by libcurl for subsequent uses. Due to a flaw in the string parser for this directory name, a directory name passed like this but without a closing double quote would lead to libcurl not adding a trailing NUL byte to the buffer holding the name. When libcurl would then later access the string, it could read beyond the allocated heap buffer and crash or wrongly access data beyond the buffer, thinking it was part of the path. A malicious server could abuse this fact and effectively prevent libcurl-based clients to work with it - the PWD command is always issued on new FTP connections and the mistake has a high chance of causing a segfault. Impact ====== An attacker is able to read sensitive information by asking curl to retrieve a maliciously crafted URL. Furthermore a malicious server can cause libcurl to segfault when connecting via FTP leading to denial of service. References ========== https://curl.haxx.se/docs/adv_20170809C.html https://curl.haxx.se/CVE-2017-1000099.patch https://curl.haxx.se/docs/adv_20170809B.html https://curl.haxx.se/CVE-2017-1000100.patch https://curl.haxx.se/docs/adv_20171004.html https://curl.haxx.se/CVE-2017-1000254.patch https://github.com/curl/curl/commit/5ff2c5ff25750aba1a8f64fbcad8e5b891512584 https://security.archlinux.org/CVE-2017-1000099 https://security.archlinux.org/CVE-2017-1000100 https://security.archlinux.org/CVE-2017-1000254