Libssh2 up to 1.8.0 SSH Server integer overflow

Summaryinfo

A vulnerability identified as critical has been detected in Libssh2 up to 1.8.0. This affects an unknown part of the component SSH Server. This manipulation causes integer overflow. This vulnerability is handled as CVE-2019-3857. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Libssh2 up to 1.8.0. Affected by this vulnerability is some unknown functionality of the component SSH Server. The manipulation with an unknown input leads to a integer overflow vulnerability. The CWE definition for the vulnerability is CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way SSH_MSG_CHANNEL_REQUEST packets with an exit signal are parsed. A remote attacker who compromises a SSH server may be able to execute code on the client system when a user connects to the server.

The bug was discovered 03/18/2019. The weakness was released 03/25/2019 by Chris Coulson as confirmed bug report (Bugzilla). It is possible to read the advisory at bugzilla.redhat.com. This vulnerability is known as CVE-2019-3857 since 01/03/2019. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available.

The vulnerability was handled as a non-public zero-day exploit for at least 7 days. During that time the estimated underground price was around $0-$5k. The commercial vulnerability scanner Qualys is able to test this issue with plugin 172157 (SUSE Enterprise Linux Security Update for libssh2_org (SUSE-SU-2019:13982-1)).

Upgrading to version 1.8.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at SecurityFocus (BID 107485†). Entries connected to this vulnerability are available at VDB-131993, VDB-131994, VDB-132104 and VDB-132105. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• Libssh2

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8.0

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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