Debian update for curl

1) Information disclosure

EUVDB-ID: #VU29292

Risk: Medium

CVSSv4.0: 4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-8169

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to cURL sends a DNS query with the provided credentials for HTTP authentication when processing redirects. A remote attacker that controls a DNS server can gain access to HTTP authenticated credentials.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Improper Neutralization of HTTP Headers for Scripting Syntax

EUVDB-ID: #VU29290

Risk: Low

CVSSv4.0: 1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-8177

CWE-ID: CWE-644 - Improper Neutralization of HTTP Headers for Scripting Syntax

Exploit availability: No

Description

The vulnerability allows a remote attacker to overwrite files on the victim's system.

The vulnerability exists due to a logical error when processing Content-Disposition: HTTP response header in curl when executed with the -J flag and -i flags in the same command line. A remote attacker can trick the victim to run a specially crafted curl command against a malicious website and overwrite files on the user's system.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Expired pointer dereference

EUVDB-ID: #VU45794

Risk: Low

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-8231

CWE-ID: CWE-825 - Expired pointer dereference

Exploit availability: No

Description

The vulnerability allows an attacker to gain access to sensitive information.

The vulnerability exists due to expired pointer dereference error for CURLOPT_CONNECT_ONLY connections that may lead to information disclosure. If the application is using the CURLOPT_CONNECT_ONLY option to check if the website is accessible, an attacker might abuse this feature and force the application to re-use expired connection and send data intended to another connection to attacker controlled server.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

4) Information disclosure

EUVDB-ID: #VU48893

Risk: Medium

CVSSv4.0: 1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-8284

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the way cURL handles PASV responses. A remote attacker with control over malicious FTP 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.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

5) Uncontrolled Recursion

EUVDB-ID: #VU48894

Risk: Low

CVSSv4.0: 1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-8285

CWE-ID: CWE-674 - Uncontrolled Recursion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due tu uncontrolled recursion when processing FTP responses within the wildcard matching functionality, which allows a callback (set with <a href="https://curl.se/libcurl/c/CURLOPT_CHUNK_BGN_FUNCTION.html">CURLOPT_CHUNK_BGN_FUNCTION</a>) to return information back to libcurl on how to handle a specific entry in a directory when libcurl iterates over a list of all available entries. A remote attacker who controls the malicious FTP server can trick the victim to connect to it and crash the application, which is using the affected libcurl version.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

6) Improper Check for Certificate Revocation

EUVDB-ID: #VU48895

Risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-8286

CWE-ID: CWE-299 - Improper Check for Certificate Revocation

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrectly implemented checks for OCSP stapling. A remote attacker can provide a fraudulent OCSP response that would appear fine, instead of the real one.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

7) Information disclosure

EUVDB-ID: #VU51821

Risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-22876

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to 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.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

8) Man-in-the-Middle (MitM) attack

EUVDB-ID: #VU51822

Risk: Medium

CVSSv4.0: 1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-22890

CWE-ID: CWE-300 - Channel Accessible by Non-Endpoint ('Man-in-the-Middle')

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to an error when handling TLS 1.3 session tickets. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. The reason for this confusion is the modified sequence from TLS 1.2 when the session ids would provided only during the TLS handshake, while in TLS 1.3 it happens post hand-shake and the code was not updated to take that changed behavior into account.

When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed.

This flaw can allow a malicious HTTPS proxy to MITM the traffic. Such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.

Mitigation

Update curl package to version 7.64.0-4+deb10u2.

Vulnerable software versions

curl (Debian package): 7.64.0 - 7.64.0-4

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4881

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

Risk	Medium
Patch available	YES
Number of vulnerabilities	8
CVE-ID	CVE-2020-8169 CVE-2020-8177 CVE-2020-8231 CVE-2020-8284 CVE-2020-8285 CVE-2020-8286 CVE-2021-22876 CVE-2021-22890
CWE-ID	CWE-200 CWE-644 CWE-825 CWE-674 CWE-299 CWE-300
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	curl (Debian package) Operating systems & Components / Operating system package or component
Vendor	Debian