Summary
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)
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 20.04 LTS 20.04:LTS | openssh | 1:8.2p1-4ubuntu0.10 |
| Ubuntu · 22.04 LTS 22.04:LTS | openssh | 1:8.9p1-3ubuntu0.5 |
Vulnerabilities 2
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Medium 5.9
Prefix Truncation Attack against ChaCha20-Poly1305 and Encrypt-then-MAC aka Terrapin
The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the extension negotiation message), and a client and server…
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Unscored —
ssh-add in OpenSSH before 9.3 adds smartcard keys to ssh-agent without the intended per-hop destination constraints. Th…