Out-of-Bounds Affecting libssh package, versions [,0.9.6)


Severity

Recommended
0.0
medium
0
10

CVSS assessment by Snyk's Security Team. Learn more

Threat Intelligence

EPSS
0.11% (30th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-UNMANAGED-LIBSSH-2379519
  • published26 Jan 2022
  • disclosed31 Aug 2021
  • creditUnknown

Introduced: 31 Aug 2021

CVE-2021-3634  (opens in a new tab)
CWE-119  (opens in a new tab)

How to fix?

Upgrade libssh to version 0.9.6 or higher.

Overview

Affected versions of this package are vulnerable to Out-of-Bounds. 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 Base Scores

version 3.1