curl before 7.53.0 has an incorrect TLS Certificate Status Request extension feature that asks for a fresh proof of the server's certificate's validity in the code that checks for a test success or failure. It ends up always thinking there's valid proof, even when there is none or if the server doesn't support the TLS extension in question. This could lead to users not detecting when a server's certificate goes invalid or otherwise be mislead that the server is in a better shape than it is in reality. This flaw also exists in the command line tool (--cert-status).
curl version curl 7.20.0 to and including curl 7.59.0 contains a CWE-126: Buffer Over-read vulnerability in denial of service that can result in curl can be tricked into reading data beyond the end of a heap based buffer used to store downloaded RTSP content.. This vulnerability appears to have been fixed in curl < 7.20.0 and curl >= 7.60.0.
curl before version 7.52.1 is vulnerable to an uninitialized random in libcurl's internal function that returns a good 32bit random value. Having a weak or virtually non-existent random value makes the operations that use it vulnerable.
curl before version 7.52.0 is vulnerable to a buffer overflow when doing a large floating point output in libcurl's implementation of the printf() functions. If there are any application that accepts a format string from the outside without necessary input filtering, it could allow remote attacks.
A buffer overflow exists in curl 7.12.3 to and including curl 7.58.0 in the FTP URL handling that allows an attacker to cause a denial of service or worse.
A buffer over-read exists in curl 7.20.0 to and including curl 7.58.0 in the RTSP+RTP handling code that allows an attacker to cause a denial of service or information leakage
The verify_certificate function in lib/vtls/schannel.c in libcurl 7.30.0 through 7.51.0, when built for Windows CE using the schannel TLS backend, makes it easier for remote attackers to conduct man-in-the-middle attacks via a crafted wildcard SAN in a server certificate, as demonstrated by "*.com."
The verify_certificate function in lib/vtls/schannel.c in libcurl 7.30.0 through 7.51.0, when built for Windows CE using the schannel TLS backend, allows remote attackers to obtain sensitive information, cause a denial of service (crash), or possibly have unspecified other impact via a wildcard certificate name, which triggers an out-of-bounds read.
libcurl 7.1 through 7.57.0 might accidentally leak authentication data to third parties. When asked to send custom headers in its HTTP requests, libcurl will send that set of headers first to the host in the initial URL but also, if asked to follow redirects and a 30X HTTP response code is returned, to the host mentioned in URL in the `Location:` response header value. Sending the same set of headers to subsequent hosts is in particular a problem for applications that pass on custom `Authorization:` headers, as this header often contains privacy sensitive information or data that could allow others to impersonate the libcurl-using client's request.