CVE-2021-3634

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Source

https://nvd.nist.gov/vuln/detail/CVE-2021-3634

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-3634.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2021-3634

Related

Published

2021-08-31T17:15:08Z

Modified

2024-09-18T03:15:21.260724Z

Severity

6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator

Summary

[none]

Details

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 secrethash and the other sessionid. Initially, both of them are the same, but after key re-exchange, previous sessionid is kept and used as an input to new secrethash. 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 "secrethash" of different size than the sessionid has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.

References

Affected packages

Debian:11 / libssh

Package

Name: libssh
Purl: pkg:deb/debian/libssh?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

0.9.5-1+deb11u1

Affected versions

0.*

0.9.5-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:12 / libssh

Package

Name: libssh
Purl: pkg:deb/debian/libssh?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

0.9.6-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:13 / libssh

Package

Name: libssh
Purl: pkg:deb/debian/libssh?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

0.9.6-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Git / gitlab.com/libssh/libssh-mirror

Affected ranges

Type: GIT
Repo: https://gitlab.com/libssh/libssh-mirror
Events: Introduced

67c0ce3d219a1565491c30d6e5815a73eaea70a4

Fixed

da6d026c125712d197479a7930b4efc117bfe7af

Affected versions

libssh-0.*

libssh-0.9.1

libssh-0.9.2

libssh-0.9.3

libssh-0.9.4

libssh-0.9.5