Ubuntu Security Notice USN-6738-1

Debian Linux Security Advisory 5750-1 - Support for the "strict kex" SSH extension has been backported to AsyncSSH (a Python implementation of the SSHv2 protocol) as hardening against the Terrapin attack.

Red Hat Security Advisory 2024-3918-03 - Red Hat OpenShift Container Platform release 4.14.30 is now available with updates to packages and images that fix several bugs and add enhancements.

Red Hat Security Advisory 2024-0722-03 - An update is now available for Red Hat build of Quarkus. Issues addressed include a denial of service vulnerability.

Red Hat Security Advisory 2024-1196-03 - A security update is now available for Red Hat JBoss Enterprise Application Platform 7.4.

Red Hat Security Advisory 2024-0538-03 - An update for libssh is now available for Red Hat Enterprise Linux 8.6 Extended Update Support. Issues addressed include bypass and null pointer vulnerabilities.

Ubuntu Security Notice 6589-1 - Fabian Baeumer, Marcus Brinkmann and Joerg Schwenk discovered that the SSH protocol used in FileZilla is prone to a prefix truncation attack, known as the "Terrapin attack". A remote attacker could use this issue to downgrade or disable some security features and obtain sensitive information.

Ubuntu Security Notice 6585-1 - Fabian Bäumer, Marcus Brinkmann, Joerg 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.

Debian Linux Security Advisory 5600-1 - Fabian Baeumer, Marcus Brinkmann and Joerg Schwenk discovered that the SSH protocol is prone to a prefix truncation attack, known as the "Terrapin attack". This attack allows a MITM attacker to effect a limited break of the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the commencement of encryption, and deleting an equal number of consecutive messages immediately after encryption starts.

Debian Linux Security Advisory 5588-1 - Fabian Baeumer, Marcus Brinkmann and Joerg Schwenk discovered that the SSH protocol is prone to a prefix truncation attack, known as the "Terrapin attack". This attack allows a MITM attacker to effect a limited break of the integrity of the early encrypted SSH transport protocol by sending extra messages prior to the commencement of encryption, and deleting an equal number of consecutive messages immediately after encryption starts.

Ubuntu Security Notice 6561-1 - Fabian Bäumer, Marcus Brinkmann, Joerg 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.

Ubuntu Security Notice 6560-1 - Fabian Bäumer, Marcus Brinkmann, Joerg 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. 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.

### Summary Russh v0.40.1 and earlier is vulnerable to a novel prefix truncation attack (a.k.a. Terrapin attack), which allows a man-in-the-middle attacker to strip an arbitrary number of messages right after the initial key exchange, breaking SSH extension negotiation (RFC8308) in the process and thus downgrading connection security. ### Mitigations To mitigate this protocol vulnerability, OpenSSH suggested a so-called "strict kex" which alters the SSH handshake to ensure a Man-in-the-Middle attacker cannot introduce unauthenticated messages as well as convey sequence number manipulation across handshakes. Support for strict key exchange has been added to Russh in the patched version. **Warning: To take effect, both the client and server must support this countermeasure.** As a stop-gap measure, peers may also (temporarily) disable the affected algorithms and use unaffected alternatives like AES-GCM instead until patches are available. ### Details The SSH specifications of Ch...