Fedora 40 update for libssh2



Risk Low
Patch available YES
Number of vulnerabilities 2
CVE-ID CVE-2023-6918
CVE-2023-48795
CWE-ID CWE-252
CWE-326
Exploitation vector Network
Public exploit Public exploit code for vulnerability #2 is available.
Vulnerable software
 Fedora
Operating systems & Components / Operating system

libssh2
Operating systems & Components / Operating system package or component

Vendor Fedoraproject

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) 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 updates from vendor's repository.

Vulnerable software versions

Fedora: 40

libssh2: before 1.11.1-1.fc40

CPE2.3 External links

https://bodhi.fedoraproject.org/updates/FEDORA-2025-aaa849ae74


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 updates from vendor's repository.

Vulnerable software versions

Fedora: 40

libssh2: before 1.11.1-1.fc40

CPE2.3 External links

https://bodhi.fedoraproject.org/updates/FEDORA-2025-aaa849ae74


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.



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