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libssh: Denial of service — GLSA 202004-08

A vulnerability in libssh could allow a remote attacker to cause a Denial of Service condition.

Affected packages

Package net-libs/libssh on all architectures
Affected versions < 0.9.4
Unaffected versions >= 0.9.4

Background

libssh is a multiplatform C library implementing the SSHv2 protocol on client and server side.

Description

It was discovered that libssh could crash when AES-CTR ciphers are used.

Impact

A remote attacker running a malicious client or server could possibly crash the counterpart implemented with libssh and cause a Denial of Service condition.

Workaround

Disable AES-CTR ciphers. If you implement a server using libssh it is recommended to use a prefork model so each session runs in an own process.

Resolution

All libssh users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-libs/libssh-0.9.4"

References

Release date
April 10, 2020

Latest revision
April 10, 2020: 1

Severity
low

Exploitable
remote

Bugzilla entries