Mageia 2021-0441: libssh security update | LinuxSecurity.com

Advisories

MGASA-2021-0441 - Updated libssh packages fix security vulnerability

Publication date: 23 Sep 2021
URL: https://advisories.mageia.org/MGASA-2021-0441.html
Type: security
Affected Mageia releases: 8
CVE: CVE-2021-3634

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. (CVE-2021-3634)

References:
- https://bugs.mageia.org/show_bug.cgi?id=29419
- https://www.libssh.org/security/advisories/CVE-2021-3634.txt
- https://www.libssh.org/2021/08/26/libssh-0-9-6-security-release/
- https://ubuntu.com/security/notices/USN-5053-1
- https://www.debian.org/security/2021/dsa-4965
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3634

SRPMS:
- 8/core/libssh-0.9.6-1.mga8

Mageia 2021-0441: libssh security update

A flaw has been found in libssh in versions prior to 0.9.6

Summary

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. (CVE-2021-3634)

References

- https://bugs.mageia.org/show_bug.cgi?id=29419

- https://www.libssh.org/security/advisories/CVE-2021-3634.txt

- https://www.libssh.org/2021/08/26/libssh-0-9-6-security-release/

- https://ubuntu.com/security/notices/USN-5053-1

- https://www.debian.org/security/2021/dsa-4965

- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3634

Resolution

MGASA-2021-0441 - Updated libssh packages fix security vulnerability

SRPMS

- 8/core/libssh-0.9.6-1.mga8

Severity
Publication date: 23 Sep 2021
URL: https://advisories.mageia.org/MGASA-2021-0441.html
Type: security
CVE: CVE-2021-3634

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