Advisory severityMedium5.9Netgate pfSense

Medium [CVE-2023-48795] pfSense: The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products

This medium-severity Netgate pfSense advisory covers CVE-2023-48795; related products: pfSense, pfSense Plus, pfSense CE.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2023-48795 Source published Dec 19, 2023Source updated Jun 17, 2026

VulniPulse record published Dec 19, 2023Record updated Jun 17, 2026

CVE-2023-48795

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Summary

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.

Affected versions

before 9.6
before 3.1.0
before 5.1.1
before 0.80
before 2.14.2
before 0.17.0
before 0.10.6
before 3.4.6
before 5.1
before 3.4.0
before 0.2.15
before 2.5.6

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Fixed versions

9.6
3.1.0-SNAPSHOT
5.1.1
0.80
2.14.2
0.17.0
0.10.6
3.4.6
5.1
3.4.0
0.2.15
2.5.6
1.3.8b
1.3.9r
2.3.4
10.6.0
2.2.22
3.66.4
11.8
14.4

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Mitigation

Upgrade to a fixed release: 9.6, 3.1.0-SNAPSHOT, 5.1.1, 0.80, 2.14.2, 0.17.0. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 3 months ago·verify at source

Discussion(0)

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