Debian Linux Security Advisory 5588-1 - 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.
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Debian Security Advisory DSA-5588-1 security@debian.org
https://www.debian.org/security/ Salvatore Bonaccorso
December 24, 2023 https://www.debian.org/security/faq
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Package : putty
CVE ID : CVE-2021-36367 CVE-2023-48795
Debian Bug : 990901
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 0.74-1+deb11u1. This update includes a fix for CVE-2021-36367.
For the stable distribution (bookworm), these problems have been fixed in
version 0.78-2+deb12u1.
We recommend that you upgrade your putty packages.
For the detailed security status of putty please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/putty
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
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