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...

URL file scheme drive letter buffer overflow

When libcurl is given either 1. a file: URL that does not use two slashes following the colon, or 2. is told that file is the default scheme to use for URLs without scheme ... and the given path starts with a drive letter and libcurl is built for Windows or DOS, then libcurl would copy the path...

TLS session resumption client cert bypass (again)

libcurl would attempt to resume a TLS session even if the client certificate had changed. That is unacceptable since a server by specification is allowed to skip the client certificate check on resume, and may instead use the old identity which was established by the previous certificate or no...

--write-out out of buffer read

There were two bugs in curl's parser for the command line option --write-out or -w for short that would skip the end of string zero byte if the string ended in a % percent or \ backslash, and it would read beyond that buffer in the heap memory and it could then potentially output pieces of that...

SSL_VERIFYSTATUS ignored

curl and libcurl support "OCSP stapling", also known as the TLS Certificate Status Request extension using the CURLOPTSSLVERIFYSTATUS option. When telling curl to use this feature, it uses that TLS extension to ask for a fresh proof of the server's certificate's validity. If the server does not...

uninitialized random

libcurl's new internal function that returns a good 32-bit random value was implemented poorly and overwrote the pointer instead of writing the value into the buffer the pointer pointed to. This random value is used to generate nonces for Digest and NTLM authentication, for generating boundary...

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...

Win CE Schannel cert name out of buffer read

curl's TLS server certificate checks are flawed on Windows CE. This vulnerability occurs in the verify certificate function when comparing a wildcard certificate name as returned by the Windows API function CertGetNameString to the hostname used to make the connection to the server. The pattern...

Win CE Schannel cert wildcard matches too much

curl's TLS server certificate checks are flawed on Windows CE. This vulnerability occurs in the verify certificate function when comparing a wildcard certificate name as returned by the Windows API function CertGetNameString to the hostname used to make the connection to the server. The...

cookie injection for other servers

If cookie state is written into a cookie jar file that is later read back and used for subsequent requests, a malicious HTTP server can inject new cookies for arbitrary domains into said cookie jar. The issue pertains to the function that loads cookies into memory, which reads the specified file...

OOB write via unchecked multiplication

In libcurl's base64 encode function, the output buffer is allocated as follows without any checks on insize: malloc insize 4 / 3 + 4 On systems with 32-bit addresses in userspace e.g. x86, ARM, x32, the multiplication in the expression wraps around if insize is at least 1GB of data. If this...

Use after free via shared cookies

libcurl explicitly allows users to share cookies between multiple easy handles that are concurrently employed by different threads. When cookies to be sent to a server are collected, the matching function collects all cookies to send and the cookie lock is released immediately afterwards. That...

URL unescape heap overflow via integer truncation

The URL percent-encoding decode function in libcurl is called curleasyunescape. Internally, even if this function would be made to allocate a destination buffer larger than 2GB, it would return that new length in a signed 32-bit integer variable, thus the length would get either truncated only or...

glob parser write/read out of bounds

The curl tool's "globbing" feature allows a user to specify a numerical range through which curl iterates. It is typically specified as 1-5, specifying the first and the last numbers in the range. Or with a-z, using letters. 1. The curl code for parsing the second unsigned number did not check fo...

double free in krb5 code

In curl's implementation of the Kerberos authentication mechanism, the function readdata in security.c is used to fill the necessary krb5 structures. When reading one of the length fields from the socket, it fails to ensure that the length parameter passed to realloc is not set to 0. This would...

curl_getdate read out of bounds

The curlgetdate converts a given date string into a numerical timestamp and it supports a range of different formats and possibilities to express a date and time. The underlying date parsing function is also used internally when parsing for example HTTP cookies possibly received from remote serve...

IDNA 2003 makes curl use wrong host

When curl is built with libidn to handle International Domain Names IDNA, it translates them to puny code for DNS resolving using the IDNA 2003 standard, while IDNA 2008 is the modern and up-to-date IDNA standard. This misalignment causes problems with for example domains using the German ß...

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...

double free in curl_maprintf

The libcurl API function called curlmaprintf can be tricked into doing a double free due to an unsafe sizet multiplication, on systems using 32-bit sizet variables. The function is also used internally in numerous situations. The function doubles an allocated memory area with realloc and allows t...

case insensitive password comparison

When reusing a connection, curl was doing case insensitive comparisons of username and password with the existing connections. This means that if an unused connection with proper credentials exists for a protocol that has connection-scoped credentials, an attacker can cause that connection to be...

curl escape and unescape integer overflows

The four libcurl functions curlescape, curleasyescape, curlunescape and curleasyunescape perform string URL percent escaping and unescaping. They accept custom string length inputs in signed integer arguments. The functions having names without "easy" being the deprecated versions of the others...

Incorrect reuse of client certificates

libcurl built on top of NSS Network Security Services incorrectly reused client certificates if a certificate from file was used for one TLS connection but no certificate set for a subsequent TLS connection. While the symptoms are similar to CVE-2016-5420 Reusing connection with wrong client cert...

TLS session resumption client cert bypass

libcurl would attempt to resume a TLS session even if the client certificate had changed. That is unacceptable since a server by specification is allowed to skip the client certificate check on resume, and may instead use the old identity which was established by the previous certificate or no...

use of connection struct after free

libcurl is vulnerable to a use after free flaw. libcurl works with easy handles using the type 'CURL ' that are objects the application creates using curleasyinit. They are the handles that are all each associated with a single transfer at a time. libcurl also has an internal struct that represen...

Reusing connections with wrong client cert

libcurl did not consider client certificates when reusing TLS connections. libcurl supports reuse of established connections for subsequent requests. It does this by keeping a few previous connections "alive" in a connection pool so that a subsequent request that can use one of them instead of...

Windows DLL hijacking

libcurl would load Windows system DLLs in a manner that may make it vulnerable to a DLL hijacking aka binary planting attack in certain configurations. libcurl has a unified code base that builds and runs on a multitude of different versions of Windows. To make that possible, when libcurl is buil...

TLS certificate check bypass with mbedTLS/PolarSSL

libcurl did not check the server certificate of TLS connections done to a host specified as an IP address, or when explicitly asked to use SSLv3. This flaw only exists when libcurl is built to use mbedTLS or PolarSSL as the TLS backend. The documentation for mbedTLS and PolarSSL wrongly says that...

remote filename path traversal in curl tool for Windows

curl does not sanitize colons in a remote filename that is used as the local filename. This may lead to a vulnerability on systems where the colon is a special path character. Currently Windows is the only OS where this vulnerability applies. curl offers command line options --remote-name also...

NTLM credentials not-checked for proxy connection reuse

libcurl reuses NTLM-authenticated proxy connections without properly making sure that the connection was authenticated with the same credentials as set for this transfer. libcurl maintains a pool of connections after a transfer has completed. The pool of connections is then gone through when a ne...

SMB send off unrelated memory contents

libcurl can get tricked by a malicious SMB server to send off data it did not intend to. In libcurl's state machine function handling the SMB protocol smbrequeststate, two length and offset values are extracted from data that has arrived over the network, and those values are subsequently used to...

lingering HTTP credentials in connection reuse

libcurl can wrongly send HTTP credentials when reusing connections. libcurl allows applications to set credentials for the upcoming transfer with HTTP Basic authentication, like with CURLOPTUSERPWD for example. Name and password. Like all other libcurl options the credentials are sticky and are...

sensitive HTTP server headers also sent to proxies

libcurl provides applications a way to set custom HTTP headers to be sent to the server by using CURLOPTHTTPHEADER. A similar option is available for the curl command-line tool with the '--header' option. When the connection passes through an HTTP proxy the same set of headers is sent to the prox...

Reusing authenticated connection when unauthenticated

libcurl keeps a pool of its last few connections around after use to facilitate easy, convenient and completely transparent connection reuse for applications. When doing HTTP requests NTLM authenticated, the entire connection becomes authenticated and not only the specific HTTP request which is...

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...

hostname out of boundary memory access

There is a private function in libcurl called fixhostname that removes a trailing dot from the hostname if there is one. The function is called after the hostname has been extracted from the URL libcurl has been told to act on. If a URL is given with a zero-length hostname, like in "http://:80" o...

Negotiate not treated as connection-oriented

libcurl keeps a pool of its last few connections around after use to facilitate easy, convenient and completely transparent connection reuse for applications. When doing HTTP requests Negotiate authenticated, the entire connection may become authenticated and not only the specific HTTP request...

URL request injection

When libcurl sends a request to a server via an HTTP proxy, it copies the entire URL into the request and sends if off. If the given URL contains line feeds and carriage returns those are sent along to the proxy too, which allows the program to for example send a separate HTTP request injected...

Secure Transport certificate check bypass

libcurl stores TLS Session IDs in its associated Session ID cache when it connects to TLS servers. In subsequent connects it reuses the entry in the cache to resume the TLS connection faster than when doing a full TLS handshake. The actual implementation for the Session ID caching varies dependin...

duphandle read out of bounds

libcurl's function curleasyduphandle has a bug that can lead to libcurl eventually sending off sensitive data that was not intended for sending. When doing an HTTP POST transfer with libcurl, you can use the CURLOPTCOPYPOSTFIELDS option to specify a memory area holding the data to send to the...

cookie leak with IP address as domain

By not detecting and rejecting domain names for partial literal IP addresses properly when parsing received HTTP cookies, libcurl can be fooled to both sending cookies to wrong sites and into allowing arbitrary sites to set cookies for others. For this problem to trigger, the client application...

cookie leak for TLDs

libcurl wrongly allows cookies to be set for Top Level Domains TLDs, thus making them apply broader than cookies are allowed. This can allow arbitrary sites to set cookies that then would get sent to a different and unrelated site or domain...

wrong reuse of connections

libcurl can in some circumstances reuse the wrong connection when asked to do transfers using other protocols than HTTP and FTP. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of...

not verifying certs for TLS to IP address / Secure Transport

When asked to do a TLS connection HTTPS, FTPS, IMAPS, etc to a URL specified with an IP address instead of a name, libcurl would wrongly not verify the server's name in the certificate. The signature whether it was signed by a trusted CA and validity whether the date was within the certificate's...

IP address wildcard certificate validation

libcurl incorrectly validates wildcard SSL certificates containing literal IP addresses. RFC 2818 covers the requirements for matching Common Names CNs and subjectAltNames in order to establish valid SSL connections. It first discusses CNs that are for hostnames, and the rules for wildcards in th...

not verifying certs for TLS to IP address / Schannel

When asked to do a TLS connection HTTPS, FTPS, IMAPS, etc to a URL specified with an IP address instead of a name, libcurl would wrongly not verify the server's name in the certificate. The signature whether it was signed by a trusted CA and validity whether the date was within the certificate's...

reuse of wrong HTTP NTLM connection

libcurl can in some circumstances reuse the wrong connection when asked to do an NTLM-authenticated HTTP or HTTPS request. libcurl features a pool of recent connections so that subsequent requests can reuse an existing connection to avoid overhead. When reusing a connection a range of criterion...

cert name check ignore with GnuTLS

This issue is almost identical to the one named CVE-2013-4545, but this problem affects a different SSL backend. libcurl is vulnerable to a case of missing out the checking of the certificate CN or SAN name field when the digital signature verification is turned off. libcurl offers two separate a...

cert name check ignore OpenSSL

libcurl is vulnerable to a case of missing out the checking of the certificate CN or SAN name field when the digital signature verification is turned off. libcurl offers two separate and independent options for verifying a server's TLS certificate. CURLOPTSSLVERIFYPEER and CURLOPTSSLVERIFYHOST. T...

URL decode buffer boundary flaw

libcurl is vulnerable to a case of bad checking of the input data which may lead to heap corruption. The function curleasyunescape decodes URL encoded strings to raw binary data. URL encoded octets are represented with %HH combinations where HH is a two-digit hexadecimal number. The decoded strin...

cookie domain tailmatch

libcurl is vulnerable to a cookie leak vulnerability when doing requests across domains with matching tails. When communicating over HTTPS and having libcurl's cookie engine enabled, libcurl stores and holds cookies for use when subsequent requests are done to hosts and paths that match those kep...