USN-6561-1

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    USN-6561-1

    Published: 19 Dec 2023Last Modified: 27 Apr 2026

    Summary: libssh vulnerability

    Details: Fabian Bäumer, Marcus Brinkmann, Jörg Schwenk discovered that the SSH protocol was vulnerable to a prefix truncation attack. If a remote attacker was able to intercept SSH communications, extension negotiation messages could be truncated, possibly leading to certain algorithms and features being downgraded. This issue is known as the Terrapin attack. This update adds protocol extensions to mitigate this issue.

    References: https://ubuntu.com/security/notices/USN-6561-1, https://ubuntu.com/security/CVE-2023-48795

    Affected packages

    Package

    Name: libssh

    Purl: pkg:deb/ubuntu/[email protected]?arch=source&distro=focal

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -0.9.3-2ubuntu2.4

    Affected versions

    0.9.0-1ubuntu1
    0.9.0-1ubuntu4
    0.9.0-1ubuntu5
    0.9.3-2ubuntu1
    0.9.3-2ubuntu2
    0.9.3-2ubuntu2.1
    0.9.3-2ubuntu2.2
    0.9.3-2ubuntu2.3

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    USN-6561-1 | CVE-DB