CVE-2020-8284

A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.

A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.

A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.\r\n\r\n Security Fix(es):\r\n\r\n Due to use of a dangling pointer, libcurl 7.29.0 through 7.71.1 can use the wrong connection when sending data.(CVE-2020-8231)\r\n\r\n curl 7.41.0 through 7.73.0 is vulnerable to an improper check for certificate revocation due to insufficient verification of the OCSP response.(CVE-2020-8286)\r\n\r\n curl 7.21.0 to and including 7.73.0 is vulnerable to uncontrolled recursion due to a stack overflow issue in FTP wildcard match parsing.(CVE-2020-8285)\r\n\r\n A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.(CVE-2020-8284)\r\n\r\n

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: FTP PASV command response can cause curl to connect to arbitrary host (CVE-2020-8284)

• curl: Malicious FTP server can trigger stack overflow when CURLOPT_CHUNK_BGN_FUNCTION is used (CVE-2020-8285)

• curl: Inferior OCSP verification (CVE-2020-8286)

• curl: Expired pointer dereference via multi API with CURLOPT_CONNECT_ONLY option set (CVE-2020-8231)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 8.4 Release Notes linked from the References section.

A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.

• trusting FTP PASV responses (CVE-2020-8284)

• trusting FTP PASV responses (CVE-2020-8284)

• trusting FTP PASV responses (CVE-2020-8284)

When curl performs a passive FTP transfer, it first tries the EPSV command and if that is not supported, it falls back to using PASV. Passive mode is what curl uses by default.

A server response to a PASV command includes the (IPv4) address and port number for the client to connect back to in order to perform the actual data transfer.

This is how the FTP protocol is designed to work.

A malicious server can use the PASV response to trick curl into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions.

If curl operates on a URL provided by a user (which by all means is an unwise setup), a user can exploit that and pass in a URL to a malicious FTP server instance without needing any server breach to perform the attack.

Due to use of a dangling pointer, libcurl 7.29.0 through 7.71.1 can use the wrong connection when sending data. (CVE-2020-8231).

A malicious server can use the FTP PASV response to trick curl 7.73.0 and earlier into connecting back to a given IP address and port, and this way potentially make curl extract information about services that are otherwise private and not disclosed, for example doing port scanning and service banner extractions. (CVE-2020-8284).

curl 7.21.0 to and including 7.73.0 is vulnerable to uncontrolled recursion due to a stack overflow issue in FTP wildcard match parsing. (CVE-2020-8285).

curl 7.41.0 through 7.73.0 is vulnerable to an improper check for certificate revocation due to insufficient verification of the OCSP response. (CVE-2020-8286).

This update for curl fixes the following issues:

• CVE-2020-8286: Fixed improper OSCP verification in the client side (bsc#1179593).
• CVE-2020-8285: Fixed a stack overflow due to FTP wildcard (bsc#1179399).
• CVE-2020-8284: Fixed an issue where a malicius FTP server could make curl connect to a different IP (bsc#1179398).

This update was imported from the SUSE:SLE-15-SP2:Update update project.

This update for curl fixes the following issues:

• CVE-2020-8286: Fixed improper OSCP verification in the client side (bsc#1179593).
• CVE-2020-8285: Fixed a stack overflow due to FTP wildcard (bsc#1179399).
• CVE-2020-8284: Fixed an issue where a malicius FTP server could make curl connect to a different IP (bsc#1179398).

This update was imported from the SUSE:SLE-15:Update update project.

These are all security issues fixed in the curl-7.79.1-1.1 package on the GA media of openSUSE Tumbleweed.

This update for curl fixes the following issues:

• CVE-2020-8284: Fixed an issue where a malicious FTP server could make curl connect to a different IP (bsc#1179398).
• CVE-2020-8285: Fixed an FTP wildcard stack overflow (bsc#1179399).

This update for curl fixes the following issues:

• CVE-2020-8286: Fixed improper OSCP verification in the client side (bsc#1179593).
• CVE-2020-8285: Fixed a stack overflow due to FTP wildcard (bsc#1179399).
• CVE-2020-8284: Fixed an issue where a malicius FTP server could make curl connect to a different IP (bsc#1179398).

This update for curl fixes the following issues:

• CVE-2020-8286: Fixed improper OSCP verification in the client side (bsc#1179593).
• CVE-2020-8285: Fixed a stack overflow due to FTP wildcard (bsc#1179399).
• CVE-2020-8284: Fixed an issue where a malicius FTP server could make curl connect to a different IP (bsc#1179398).

This update for curl fixes the following issues:

• CVE-2020-8286: Fixed improper OSCP verification in the client side (bsc#1179593).
• CVE-2020-8285: Fixed a stack overflow due to FTP wildcard (bsc#1179399).
• CVE-2020-8284: Fixed an issue where a malicius FTP server could make curl connect to a different IP (bsc#1179398).

This update for curl fixes the following issues:

• CVE-2021-22898: TELNET stack contents disclosure (bsc#1186114)
• CVE-2021-22876: The automatic referer leaks credentials (bsc#1183933)
• CVE-2020-8286: Inferior OCSP verification (bsc#1179593)
• CVE-2020-8285: FTP wildcard stack overflow (bsc#1179399)
• CVE-2020-8284: Trusting FTP PASV responses (bsc#1179398)
• CVE-2020-8231: libcurl will pick and use the wrong connection with multiple requests with libcurl's multi API and the 'CURLOPT_CONNECT_ONLY' option (bsc#1175109)
• Fix: SFTP uploads result in empty uploaded files (bsc#1177976)

Marc Aldorasi discovered that curl incorrectly handled the libcurl CURLOPT_CONNECT_ONLY option. This could result in data being sent to the wrong destination, possibly exposing sensitive information. This issue only affected Ubuntu 20.10. (CVE-2020-8231)

Varnavas Papaioannou discovered that curl incorrectly handled FTP PASV responses. An attacker could possibly use this issue to trick curl into connecting to an arbitrary IP address and be used to perform port scanner and other information gathering. (CVE-2020-8284)

It was discovered that curl incorrectly handled FTP wildcard matchins. A remote attacker could possibly use this issue to cause curl to consume resources and crash, resulting in a denial of service. (CVE-2020-8285)

It was discovered that curl incorrectly handled OCSP response verification. A remote attacker could possibly use this issue to provide a fraudulent OCSP response. (CVE-2020-8286)

USN-4665-1 fixed several vulnerabilities in curl. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM.

Original advisory details:

Varnavas Papaioannou discovered that curl incorrectly handled FTP PASV responses. An attacker could possibly use this issue to trick curl into connecting to an arbitrary IP address and be used to perform port scanner and other information gathering. (CVE-2020-8284)

It was discovered that curl incorrectly handled FTP wildcard matchins. A remote attacker could possibly use this issue to cause curl to consume resources and crash, resulting in a denial of service. (CVE-2020-8285)