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

🗓️ 25 Dec 2023 08:00:00Reported by MicrosoftType

mscve

mscve🔗 msrc.microsoft.com👁 6 Views

Terrapin attack enables integrity bypass in Secure Shell due to faulty handshake and sequence handling, downgrading security.

Reporter	Title	Published	Views	Family All 1459
OSV	CGA-WWR9-QF7Q-6JQM	6 Jun 202412:29	–	osv
OSV	CGA-WXVM-F23G-5XGQ	6 Jun 202412:29	–	osv
OSV	CGA-X343-VM5H-F9W3	6 Jun 202412:29	–	osv
OSV	CGA-X54V-H4QH-2466	6 Jun 202412:29	–	osv
OSV	CGA-X68G-QMF2-VHPX	6 Jun 202412:29	–	osv
OSV	CGA-X69J-449J-F37G	6 Jun 202412:26	–	osv
OSV	CGA-XC48-24MH-C3JM	6 Jun 202412:29	–	osv
OSV	CGA-XC4M-6PWQ-XFX2	6 Jun 202412:26	–	osv
OSV	CGA-XC4Q-2GGF-44W2	6 Jun 202412:26	–	osv
OSV	CGA-XFW2-PP3Q-2VR9	6 Jun 202412:26	–	osv

Vulners

Node

OR

microsoft azl3_node-problem-detector_0.8.15-4Range<0.8.20-2

microsoft azl3_docker-buildx_0.12.1-1Range<0.14.0-1

microsoft azl3_packer_1.9.4-1Range<1.9.5-1

microsoft azl3_openssh_9.8p1-4

microsoft azl3_kubernetes_1.29.1-4Range<1.30.1-1

microsoft azl3_erlang_26.2.5.12-1Range<26.2.3-2

microsoft azl3_cert-manager_1.11.2-8Range<1.12.12-1

microsoft azl3_cert-manager_1.12.12-1Range<1.12.12-1

microsoft azl3_cf-cli_8.7.11-1Range<8.7.11-1

microsoft azl3_erlang_26.2.3-1Range<26.2.3-1

microsoft azl3_kubernetes_1.30.1-1Range<1.30.1-1

microsoft azl3_kubevirt_1.2.0-9Range<1.2.0-9

microsoft azl3_libssh_0.10.6-1Range<0.10.6-1

microsoft azl3_libssh2_1.11.1-1Range<1.11.1-1

microsoft azl3_nmap_7.93-2Range<7.93-2

microsoft azl3_packer_1.9.5-1Range<1.9.5-1

microsoft azl3_docker-buildx_0.14.0-1Range<0.14.0-1

microsoft azl3_node-problem-detector_0.8.20-2Range<0.8.20-2

microsoft cbl2_cert-manager_1.11.2-7Range<1.11.2-7

microsoft cbl2_erlang_25.2-1Range<25.2-1

microsoft cbl2_libssh_0.10.6-1Range<0.10.6-1

microsoft cbl2_libssh2_1.9.0-4Range<1.9.0-4

microsoft cbl2_nmap_7.93-2Range<7.93-2

microsoft cbl2_openssh_8.9p1-4Range<8.9p1-4

microsoft cbl2_kubernetes_1.28.4-4Range<1.28.4-4

microsoft cbl2_kubevirt_0.59.0-26Range<0.59.0-26

microsoft cbl2_moby-cli_20.10.27-2Range<20.10.27-2

microsoft cbl2_moby-compose_2.17.3-5Range<2.17.3-5

microsoft cbl2_packer_1.9.5-3Range<1.9.5-3

microsoft cbl2_terraform_1.3.2-25Range<1.3.2-25

microsoft cbl2_jsch_0.1.55-2Range<0.1.55-2

microsoft cbl2_moby-engine_20.10.27-1Range<20.10.27-1

microsoft azl3_libssh_0.10.5-2Range<0.10.6-1

microsoft azl3_kubevirt_1.2.0-17Range<1.2.0-9

microsoft azl3_cf-cli_8.7.3-6Range<8.7.11-1

18 Feb 2026 23:07Current

6.8Medium risk

Vulners AI Score6.8

CVSS 3.15.9

EPSS0.93305

SSVC

Terrapin attack Secure Shell Open SSH handshake fault sequence handling ChaCha20-Poly1305 Encrypt then MAC