SB2025031246 - Fedora 40 update for libssh2

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Main Vulnerability Database SB2025031246

SB2025031246 - Fedora 40 update for libssh2

Published: March 12, 2025

Security Bulletin ID SB2025031246
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 vulnerabilities.


1) Unchecked Return Value (CVE-ID: CVE-2023-6918)

CWE-ID: CWE-252 - Unchecked Return Value

CVSSv4: 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


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.


2) Inadequate encryption strength (CVE-ID: CVE-2023-48795)

CWE-ID: CWE-326 - Inadequate Encryption Strength

CVSSv4: 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


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.


Remediation

Install update from vendor's website.

References