Уязвимость функции sendto программного средства для взаимодействия с серверами curl, позволяющая нарушителю вызвать отказ в обслуживании или осуществить перенаправление трафика

Уязвимость синтаксического анализатора программного средства для взаимодействия с серверами curl, позволяющая нарушителю выполнить чтение за границами буфера в памяти

The curl_easy_duphandle function in libcurl 7.17.1 through 7.38.0, when running with the CURLOPT_COPYPOSTFIELDS option, does not properly copy HTTP POST data for an easy handle, which triggers an out-of-bounds read that allows remote web servers to read sensitive memory information.

CRLF injection vulnerability in libcurl 6.0 through 7.x before 7.40.0, when using an HTTP proxy, allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via CRLF sequences in a URL.

The darwinssl_connect_step1 function in lib/vtls/curl_darwinssl.c in libcurl 7.31.0 through 7.39.0, when using the DarwinSSL (aka SecureTransport) back-end for TLS, does not check if a cached TLS session validated the certificate when reusing the session, which allows man-in-the-middle attackers to spoof servers via a crafted certificate.

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.

libcurl may read outside of a heap allocated buffer when doing FTP. 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. The simple fact that this has issue remained undiscovered for this long could suggest that malformed PWD responses are rare in benign servers. We are not aware of any exploit of this flaw. This bug was introduced in commit [415d2e7cb7](https://github.com/curl/curl/commit/415d2e7cb7), March 2005. In libcurl version 7.56.0, the parser always zero terminates the string but also rejects it if not terminated properly with a final double quote.