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Debian Security Advisory DSA-5591-1                   security@debian.org
https://www.debian.org/security/                     Salvatore Bonaccorso
December 28, 2023                     https://www.debian.org/security/faq
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Package        : libssh
CVE ID         : CVE-2023-6004 CVE-2023-6918 CVE-2023-48795
Debian Bug     : 1059004 1059059 1059061

Several vulnerabilities were discovered in libssh, a tiny C SSH library.

CVE-2023-6004

    It was reported that using the ProxyCommand or the ProxyJump feature
    may allow an attacker to inject malicious code through specially
    crafted hostnames.

CVE-2023-6918

    Jack Weinstein reported that missing checks for return values for
    digests may result in denial of service (application crashes) or
    usage of uninitialized memory.

CVE-2023-48795

    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.

    Details can be found at https://terrapin-attack.com/

For the oldstable distribution (bullseye), these problems have been fixed
in version 0.9.8-0+deb11u1.

For the stable distribution (bookworm), these problems have been fixed in
version 0.10.6-0+deb12u1.

We recommend that you upgrade your libssh packages.

For the detailed security status of libssh please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/source-package/libssh

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/

Mailing list: debian-security-announce@lists.debian.org

Debian: DSA-5591-1: libssh security update

December 28, 2023
Several vulnerabilities were discovered in libssh, a tiny C SSH library

Summary

CVE-2023-6004

It was reported that using the ProxyCommand or the ProxyJump feature
may allow an attacker to inject malicious code through specially
crafted hostnames.

CVE-2023-6918

Jack Weinstein reported that missing checks for return values for
digests may result in denial of service (application crashes) or
usage of uninitialized memory.

CVE-2023-48795

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.

Details can be found at https://terrapin-attack.com/

For the oldstable distribution (bullseye), these problems have been fixed
in version 0.9.8-0+deb11u1.

For the stable distribution (bookworm), these problems have been fixed in
version 0.10.6-0+deb12u1.

We recommend that you upgrade your libssh packages.

For the detailed security status of libssh please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/source-package/libssh

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/

Mailing list: debian-security-announce@lists.debian.org

Severity
Several vulnerabilities were discovered in libssh, a tiny C SSH library.

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