CVE-2021-3634

描述

A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating "secret_hash" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.

如何修補 CVE-2021-3634

要修補 CVE-2021-3634,請將受影響套件升級到下列已修補版本。

• —升級至 0.9.5-1+deb11u1 或更新版本
• —升級至 0.9.5-1+deb11u1 或更新版本

CVE-2021-3634 正在被利用嗎?

低 — EPSS 為 4.7%,目前沒有觀察到大規模利用活動。

受影響套件(2)

• from 0, < 0.9.5-1+deb11u1
• from 0, < 0.9.5-1+deb11u1

CVSS 分數

參考連結(1)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-3634