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Bug 920280 (CVE-2023-48795)

Summary: [Tracker] Terrapin Vulnerability
Product: Gentoo Security Reporter: Christopher Fore <csfore>
Component: VulnerabilitiesAssignee: Gentoo Security <security>
Status: CONFIRMED ---    
Severity: normal CC: base-system, d, embedded, hanno
Priority: Normal Keywords: Tracker
Version: unspecified   
Hardware: All   
OS: Linux   
Package list:
Runtime testing required: ---
Bug Depends on: 920293, 920299, 920304, 920385, 920421, 920682, 921290, 930152, 920291, 920292    
Bug Blocks:    

Description Christopher Fore 2023-12-18 17:03:28 UTC
CVE-2023-48795 (

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 may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and mishandles use of sequence numbers. For example, there is an effective attack against ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in and (if CBC is used) the MAC algorithms. This also affects Maverick Synergy Java SSH API before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, and PuTTY before 0.80; and there could be effects on Bitvise SSH through 9.31, AsyncSSH through 2.14.1, libssh through 0.10.5, and through 2023-12-17.
Comment 1 David Sardari 2023-12-18 19:13:13 UTC
I've used the following command to mitigate on the client side:

sed -i "1i Ciphers -$(ssh -Q cipher | grep -e -e -cbc | paste -d, -s -)" ~/.ssh/config

In my case, the following line got added before the first line of the file:

Ciphers -3des-cbc,aes128-cbc,aes192-cbc,aes256-cbc,
Comment 2 Hanno Böck gentoo-dev 2023-12-19 07:40:07 UTC
CVE-2023-46445 and CVE-2023-46446 are issues in AsyncSSH, which Gentoo has not packaged, so I believe they are irellevant here.

Only CVE-2023-48795 refers to the Terrapin vulnerability in the SSH protocol itself that affects pretty much every SSH implementation.
Comment 3 Andreas Sturmlechner gentoo-dev 2024-04-20 13:12:58 UTC
Why was kde proj CCed here at all?
Comment 4 Christopher Fore 2024-04-20 16:47:53 UTC
(In reply to Andreas Sturmlechner from comment #3)
> Why was kde proj CCed here at all?

Looks it it might have carried over from this bug: