Information Exposure Affecting curl package, versions <7.55.0-1

Note: Versions mentioned in the description apply only to the upstream curl package and not the curl package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

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 endto() 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. Limit curl's redirect protocols with --proto-redir and libcurl's with CURLOPT_REDIR_PROTOCOLS.

• https://security-tracker.debian.org/tracker/CVE-2017-1000100
• https://support.apple.com/HT208221
• https://curl.haxx.se/docs/adv_20170809B.html
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-1000100
• http://www.debian.org/security/2017/dsa-3992
• https://security.gentoo.org/glsa/201709-14
• https://access.redhat.com/errata/RHSA-2018:3558
• http://www.securityfocus.com/bid/100286
• http://www.securitytracker.com/id/1039118
• http://people.ubuntu.com/~ubuntu-security/cve/CVE-2017-1000100