TFTP sends more than buffer size
When doing a TFTP transfer and curl/libcurl is given a URL that contains a long filename (longer than about 515 bytes), the filename is truncated to fit within the buffer boundaries, but the buffer size is still wrongly updated to use the original 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 then reads 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 has not 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`.
02 / AFFECTED SOFTWARE
Affected packages
158 explicit affected versions
160 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
When doing a TFTP transfer and curl/libcurl is given a URL that contains a long filename (longer than about 515 bytes), the filename is truncated to fit within the buffer boundaries, but the buffer size is still wrongly updated to use the original 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 then reads 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 has not 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`.
05 / REFERENCES