- Vulnerability/
- USN-6560-1
USN-6560-1: OpenSSH vulnerabilities
First published: Tue Dec 19 2023(Updated: )
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. (CVE-2023-48795) Luci Stanescu discovered that OpenSSH incorrectly added destination constraints when smartcard keys were added to ssh-agent, contrary to expectations. This issue only affected Ubuntu 22.04 LTS, and Ubuntu 23.04. (CVE-2023-28531)
| Affected Software | Affected Version | How to fix |
|---|---|---|
| All of | ||
| ubuntu/openssh-client | <1:9.3p1-1ubuntu3.1 | 1:9.3p1-1ubuntu3.1 |
| Ubuntu | =23.10 | |
| All of | ||
| ubuntu/openssh-server | <1:9.3p1-1ubuntu3.1 | 1:9.3p1-1ubuntu3.1 |
| Ubuntu | =23.10 | |
| All of | ||
| ubuntu/openssh-client | <1:9.0p1-1ubuntu8.6 | 1:9.0p1-1ubuntu8.6 |
| Ubuntu | =23.04 | |
| All of | ||
| ubuntu/openssh-server | <1:9.0p1-1ubuntu8.6 | 1:9.0p1-1ubuntu8.6 |
| Ubuntu | =23.04 | |
| All of | ||
| ubuntu/openssh-client | <1:8.9p1-3ubuntu0.5 | 1:8.9p1-3ubuntu0.5 |
| Ubuntu | =22.04 | |
| All of | ||
| ubuntu/openssh-server | <1:8.9p1-3ubuntu0.5 | 1:8.9p1-3ubuntu0.5 |
| Ubuntu | =22.04 | |
| All of | ||
| ubuntu/openssh-client | <1:8.2p1-4ubuntu0.10 | 1:8.2p1-4ubuntu0.10 |
| Ubuntu | =20.04 | |
| All of | ||
| ubuntu/openssh-server | <1:8.2p1-4ubuntu0.10 | 1:8.2p1-4ubuntu0.10 |
| Ubuntu | =20.04 |
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Reference Links
- https://ubuntu.com/security/CVE-2023-48795
- https://ubuntu.com/security/CVE-2023-28531
- https://ubuntu.com/security/notices/USN-6561-1
- https://ubuntu.com/security/notices/USN-6560-2
- https://ubuntu.com/security/notices/USN-6585-1
- https://ubuntu.com/security/notices/USN-6589-1
- https://ubuntu.com/security/notices/USN-6598-1
- https://ubuntu.com/security/notices/USN-6738-1
- https://ubuntu.com/security/notices/USN-7051-1
- https://ubuntu.com/security/notices/USN-7292-1
- https://ubuntu.com/security/notices/USN-7297-1
- https://launchpad.net/ubuntu/+source/openssh/1:9.3p1-1ubuntu3.1
- https://launchpad.net/ubuntu/+source/openssh/1:9.0p1-1ubuntu8.6
- https://launchpad.net/ubuntu/+source/openssh/1:8.9p1-3ubuntu0.5
- https://launchpad.net/ubuntu/+source/openssh/1:8.2p1-4ubuntu0.10
- https://ubuntu.com/security/notices/USN-6560-1 (Advisory)
Frequently Asked Questions
What is the severity of USN-6560-1?
USN-6560-1 has a high severity due to its potential to allow remote attackers to intercept and manipulate SSH communications.
How do I fix USN-6560-1?
To fix USN-6560-1, you should update your OpenSSH package to the latest version available for your Ubuntu release.
Which versions of OpenSSH are affected by USN-6560-1?
USN-6560-1 affects multiple versions of OpenSSH, specifically those before 1:9.3p1-1ubuntu3.1, 1:9.0p1-1ubuntu8.6, and earlier versions.
What types of attacks can USN-6560-1 lead to?
USN-6560-1 can lead to prefix truncation attacks that compromise the integrity of SSH extension negotiation.
Is there any workaround for USN-6560-1?
There are no known workarounds for USN-6560-1, so the best course of action is to apply the recommended updates.
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