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 SSH's use of ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in [email protected] and (if CBC is used) the [email protected] 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, PuTTY before 0.80, AsyncSSH before 2.14.2, golang.org/x/crypto before 0.17.0, libssh before 0.10.6, libssh2 through 1.11.0, Thorn Tech SFTP Gateway before 3.4.6, Tera Term before 5.1, Paramiko before 3.4.0, jsch before 0.2.15, SFTPGo before 2.5.6, Netgate pfSense Plus through 23.09.1, Netgate pfSense CE through 2.7.2, HPN-SSH through 18.2.0, ProFTPD before 1.3.8b (and before 1.3.9rc2), ORYX CycloneSSH before 2.3.4, NetSarang XShell 7 before Build 0144, CrushFTP before 10.6.0, ConnectBot SSH library before 2.2.22, Apache MINA sshd through 2.11.0, sshj through 0.37.0, TinySSH through 20230101, trilead-ssh2 6401, LANCOM LCOS and LANconfig, FileZilla before 3.66.4, Nova before 11.8, PKIX-SSH before 14.4, SecureCRT before 9.4.3, Transmit5 before 5.10.4, Win32-OpenSSH before 9.5.0.0p1-Beta, WinSCP before 6.2.2, Bitvise SSH Server before 9.32, Bitvise SSH Client before 9.33, KiTTY through 0.76.1.13, the net-ssh gem 7.2.0 for Ruby, the mscdex ssh2 module before 1.15.0 for Node.js, the thrussh library before 0.35.1 for Rust, and the Russh crate before 0.40.2 for Rust.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
dropbear	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Ignored
filezilla	24.04 LTS noble	Fixed 3.66.4-1
	23.10 mantic	Fixed 3.65.0-3ubuntu0.1
	23.04 lunar	Ignored
	22.04 LTS jammy	Fixed 3.58.0-1ubuntu0.1
	20.04 LTS focal	Fixed 3.46.3-1ubuntu0.1
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release
golang-go.crypto	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Ignored
libssh	24.04 LTS noble	Not affected
	23.10 mantic	Fixed 0.10.5-3ubuntu1.1
	23.04 lunar	Fixed 0.10.4-2ubuntu0.2
	22.04 LTS jammy	Fixed 0.9.6-2ubuntu0.22.04.2
	20.04 LTS focal	Fixed 0.9.3-2ubuntu2.4
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Ignored
libssh2	24.04 LTS noble	Not affected
	23.10 mantic	Fixed 1.11.0-2ubuntu0.1
	23.04 lunar	Not affected
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected
lxd	24.04 LTS noble	Not in release
	23.10 mantic	Not in release
	23.04 lunar	Not in release
	22.04 LTS jammy	Not in release
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Fixed 3.0.3-0ubuntu1~18.04.2+esm1 Ubuntu Pro
	16.04 LTS xenial	Fixed 2.0.11-0ubuntu1~16.04.4+esm1 Ubuntu Pro
	14.04 LTS trusty	Not in release
openssh	24.04 LTS noble	Fixed 1:9.6p1-3ubuntu1
	23.10 mantic	Fixed 1:9.3p1-1ubuntu3.1
	23.04 lunar	Fixed 1:9.0p1-1ubuntu8.6
	22.04 LTS jammy	Fixed 1:8.9p1-3ubuntu0.5
	20.04 LTS focal	Fixed 1:8.2p1-4ubuntu0.10
	18.04 LTS bionic	Fixed 1:7.6p1-4ubuntu0.7+esm3 Ubuntu Pro
	16.04 LTS xenial	Fixed 1:7.2p2-4ubuntu2.10+esm5 Ubuntu Pro
	14.04 LTS trusty	Needs evaluation
openssh-ssh1	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Not in release
paramiko	24.04 LTS noble	Fixed 2.12.0-2ubuntu4
	23.10 mantic	Fixed 2.12.0-2ubuntu1.23.10.2
	23.04 lunar	Ignored
	22.04 LTS jammy	Fixed 2.9.3-0ubuntu1.2
	20.04 LTS focal	Fixed 2.6.0-2ubuntu0.3
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Needs evaluation
proftpd-dfsg	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Ignored
putty	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Ignored
python-asyncssh	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Not in release
snapd	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored
	23.04 lunar	Ignored
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Ignored

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Notes

mdeslaur

Per upstream openssh developers: While cryptographically novel, the security impact of this attack is fortunately very limited as it only allows deletion of consecutive messages, and deleting most messages at this stage of the protocol prevents user user authentication from proceeding and results in a stuck connection. The most serious identified impact is that it lets a MITM to 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. There is no other discernable impact to session secrecy or session integrity.

sbeattie

putty fixes include some refactoring commits that are used by the added strict kex mode support

seth-arnold

openssh-ssh1 is provided for compatibility with old devices that cannot be upgraded to modern protocols. Thus we may not provide security support for this package if doing so would prevent access to equipment.

jdstrand

snapd contains an embedded copy of golang-go.crypto lxd in 18.04 LTS and earlier contains an embedded copy of golang-go.crypto

sbeattie

proftpd-dfsg contains an ssh implementation in mod-sftp (distributed in proftpd-mod-crypto/proftpd-basic)

mdeslaur

per Debian, libssh2 older than mantic isn't vulnerable as it doesn't support ChaCha20-Poly1305 and CBC-EtM.

ccdm94

libssh will be marked as not affected for bionic and earlier as per the above note. ChaCha20-Poly1305 and CBC-EtM are present only in libssh 0.8.0 (released 2018-08-10. Bionic is version 0.8.0, but based on commit 94fa1e38, which was released 2017-08-25) and later. Patches provided by upstream do not apply cleanly to versions in bionic and earlier as several functionalities are not present in these versions of the code (making backports a more likely to introduce regressions) further supporting the defined not affected status.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
dropbear	Upstream: 6e43be5
golang-go.crypto	Upstream: 9d2ee97
libssh	Upstream: 4cef5e9 Upstream: 0870c8d Upstream: 5846e57 Upstream: 89df759
libssh2	Upstream: d34d925 Upstream: https://github.com/libssh2/libssh2/pull/1291
openssh	Upstream: 1edb00c
paramiko	Upstream: be3ffc1 Upstream: 4c7f041 Upstream: 773a174 Upstream: c32be44 Upstream: f4dedac Upstream: 73f079f Upstream: 75e311d Upstream: fa46de7 Upstream: 8dcb237 Upstream: 58785d2 Upstream: 96db1e2 Upstream: 33508c9 Upstream: 30b447b Upstream: 3e4bdf9
putty	Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=9e099151574885f3c717ac10a633a9218db8e7bb Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=f2e7086902b3605c96e54ef9c956ca7ab000010e Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=9fcbb86f715bc03e58921482efe663aa0c662d62 Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=244be5412728a7334a2d457fbac4e0a2597165e5 Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=58fc33a155ad496bdcf380fa6193302240a15ae9 Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=0b00e4ce26d89cd010e31e66fd02ac77cb982367 Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=fdc891d17063ab26cf68c74245ab1fd9771556cb Upstream: https://git.tartarus.org/?p=simon/putty.git;a=commit;h=b80a41d386dbfa1b095c17bd2ed001477f302d46
python-asyncssh	Upstream: 0bc7325
snapd	Upstream: https://github.com/snapcore/snapd/pull/14143

Severity score breakdown

Parameter	Value
Base score	5.9 · Medium
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-6560-1
OpenSSH vulnerabilities
19 December 2023

USN-6561-1
libssh vulnerability
19 December 2023

USN-6560-2
OpenSSH vulnerabilities
11 January 2024

USN-6585-1
libssh2 vulnerability
15 January 2024

USN-6589-1
FileZilla vulnerability
18 January 2024

USN-6598-1
Paramiko vulnerability
25 January 2024

USN-6738-1
LXD vulnerability
22 April 2024

CVE-2023-48795

Cvss 3 Severity Score

Status

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Notes

mdeslaur

sbeattie

seth-arnold

jdstrand

sbeattie

mdeslaur

ccdm94

Patch details

Severity score breakdown

References

Related Ubuntu Security Notices (USN)

Other references