Set-Cookie denial of service

A malicious server can serve excessive amounts of Set-Cookie: headers in a HTTP response to curl and curl stores all of them. A sufficiently large amount of big cookies make subsequent HTTP requests to this, or other servers to which the cookies match, create requests that become larger than the...

Non-preserved file permissions

When curl saves cookies, alt-svc and hsts data to local files, it makes the operation atomic by finalizing the operation with a rename from a temporary name to the final target filename. In that rename operation, it might accidentally widen the permissions for the target file, leaving the updated...

percent-encoded path separator in URL host

The curl URL parser wrongly accepts percent-encoded URL separators like '/' when decoding the hostname part of a URL, making it a different URL using the wrong hostname when it is later retrieved. For example, a URL like http://example.com%2F10.0.0.1/, would be allowed by the parser and get...

Auth/cookie leak on redirect

curl might leak authentication or cookie header data on HTTP redirects to the same host but another port number. When asked to send custom headers or cookies in its HTTP requests, curl sends that set of headers only to the host which name is used in the initial URL, so that redirects to other hos...

Bad local IPv6 connection reuse

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse, if one of them matches the setup. Due to errors in the logic, the config matching function did not take the IPv6 address zone id into account which could lead to libcurl reusing the wrong connection...

warning message out-of-buffer read

curl contains a heap out of buffer read vulnerability. The command line tool has a generic function for displaying warning and informational messages to stderr for various situations. For example if an unknown command line argument is used, or passed to it in a "config" file. This display functio...

FTP path trickery leads to NIL byte out of bounds write

curl can be fooled into writing a zero byte out of bounds. This bug can trigger when curl is told to work on an FTP URL, with the setting to only issue a single CWD command --ftp-method singlecwd or the libcurl alternative CURLOPTFTPFILEMETHOD. curl then URL-decodes the given path, calls strlen o...

invalid URL parsing with '#'

curl does not parse the authority component of the URL correctly when the host name part ends with a hash character, and could instead be tricked into connecting to a different host. This may have security implications if you for example use a URL parser that follows the RFC to check for allowed...

TFTP Packet Buffer Overflow

libcurl uses the given file part of a TFTP URL in a manner that allows a malicious user to overflow a heap-based memory buffer due to the lack of boundary check. This overflow happens if you pass in a URL with a TFTP protocol prefix "tftp://", using a valid host and a path part that is longer tha...

HSTS bypass via trailing dot

curl's HSTS check could be bypassed to trick it to keep using HTTP. Using its HSTS support, curl can be instructed to use HTTPS directly instead of using an insecure clear-text HTTP step even when HTTP is provided in the URL. This mechanism could be bypassed if the hostname in the given URL used ...

CERTINFO never-ending busy-loop

libcurl provides the CURLOPTCERTINFO option to allow applications to request details to be returned about a TLS server's certificate chain. Due to an erroneous function, a malicious server could make libcurl built with NSS get stuck in a never-ending busy-loop when trying to retrieve that...

Automatic referer leaks credentials

libcurl does not strip off user credentials from the URL when automatically populating the Referer: HTTP request header field in outgoing HTTP requests, and therefore risks leaking sensitive data to the server that is the target of the second HTTP request. libcurl automatically sets the Referer:...

printf floating point buffer overflow

libcurl's implementation of the printf functions triggers a buffer overflow when doing a large floating point output. The bug occurs when the conversion outputs more than 255 bytes. The flaw happens because the floating point conversion is using system functions without the correct boundary check...

cookie parser out of boundary memory access

libcurl supports HTTP "cookies" as documented in RFC 6265. Together with each individual cookie there are several different properties, but for this vulnerability we focus on the associated "path" element. It tells information about for which path on a given host the cookie is valid. The internal...

URL Buffer Overflow

libcurl's URL parser function can overflow a heap based buffer in two ways, if given a too long URL. These overflows happen if you 1 - pass in a URL with no protocol like "http://" prefix, using no slash and the string is 256 bytes or longer. This leads to a single zero byte overflow of the heap...