Out-of-bounds Write Affecting libssh-devel package, versions <0:0.9.6-3.el8


Severity

Recommended
low

Based on Rocky Linux security rating.

Threat Intelligence

EPSS
0.67% (80th percentile)

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  • Snyk IDSNYK-ROCKY8-LIBSSHDEVEL-3200274
  • published5 Jan 2023
  • disclosed31 Aug 2021

Introduced: 31 Aug 2021

CVE-2021-3634  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Rocky-Linux:8 libssh-devel to version 0:0.9.6-3.el8 or higher.
This issue was patched in RLSA-2022:2031.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libssh-devel package and not the libssh-devel package as distributed by Rocky-Linux. See How to fix? for Rocky-Linux:8 relevant fixed versions and status.

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.

CVSS Scores

version 3.1