SB2025022558 - Ubuntu update for dropbear

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Main Vulnerability Database SB2025022558

SB2025022558 - Ubuntu update for dropbear

Published: February 25, 2025

Security Bulletin ID SB2025022558
Severity
Medium
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Medium 50% Low 50%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 secuirty vulnerabilities.


1) Improper authentication (CVE-ID: CVE-2021-36369)

The vulnerability allows a remote user to bypass authentication process.

The vulnerability exists due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code. A remote user can bypass additional security measures such as FIDO2 tokens or SSH-Askpass and abuse a forwarded agent for logging on to another server unnoticed.


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

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