Multiple vulnerabilities in libssh

Published: 2023-12-19 | Updated: 2025-01-31

Risk	Medium
Patch available	YES
Number of vulnerabilities	3
CVE-ID	CVE-2023-6004 CVE-2023-48795 CVE-2023-6918
CWE-ID	CWE-78 CWE-326 CWE-252
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #2 is available.
Vulnerable software	libssh Universal components / Libraries / Libraries used by multiple products
Vendor	libssh

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) OS Command Injection

EUVDB-ID: #VU84538

Risk: Medium

CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2023-6004

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to improper input validation in OpenSSH client. If an invalid user or hostname that contained shell metacharacters was passed to ssh(1), and a ProxyCommand, LocalCommand directive or "match exec" predicate referenced the user or hostname via %u, %h or similar expansion token, then an attacker who could supply arbitrary user/hostnames to ssh(1) could potentially perform command injection depending on what quoting was present in the user-supplied ssh_config(5) directive.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libssh: 0.3.0 - 0.10.5

CPE2.3

External links

https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/
https://www.libssh.org/security/advisories/CVE-2023-6004.txt

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) Inadequate encryption strength

EUVDB-ID: #VU84537

Risk: Low

CVSSv4.0: 2.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2023-48795

CWE-ID: CWE-326 - Inadequate Encryption Strength

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists due to incorrect implementation of the SSH Binary Packet Protocol (BPP), which mishandles the handshake phase and the use of sequence numbers. A remote attacker can perform MitM attack and delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.

The vulnerability was dubbed "Terrapin attack" and it affects both client and server implementations.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libssh: 0.3.0 - 0.10.5

CPE2.3

External links

https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/
https://www.libssh.org/security/advisories/CVE-2023-48795.txt

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. However, proof of concept for this vulnerability is available.

3) Unchecked Return Value

EUVDB-ID: #VU84540

Risk: Low

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

CVE-ID: CVE-2023-6918

CWE-ID: CWE-252 - Unchecked Return Value

Exploit availability: No

Description

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

The vulnerability exists due to libssh does not check for returned values of message digest (MD) operations in low memory conditions. A remote attacker can terminate the connection or force the library to use weak keys.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libssh: 0.3.0 - 0.10.5

CPE2.3

External links

https://bugzilla.redhat.com/show_bug.cgi?id=2254997
https://www.libssh.org/2023/12/18/libssh-0-10-6-and-libssh-0-9-8-security-releases/
https://www.libssh.org/security/advisories/CVE-2023-6918.txt

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.