Libssh2 up to 1.8.x kex.c integer overflow

Summaryinfo

A vulnerability, which was classified as critical, has been found in Libssh2 up to 1.8.x. Impacted is the function kex_method_diffie_hellman_group_exchange_sha256_key_exchange in the library libssh2_check_length of the file kex.c. The manipulation leads to integer overflow. This vulnerability is traded as CVE-2019-13115. It is possible to initiate the attack remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Libssh2 up to 1.8.x and classified as critical. This issue affects the function kex_method_diffie_hellman_group_exchange_sha256_key_exchange in the library libssh2_check_length of the file kex.c. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In libssh2 before 1.9.0, kex_method_diffie_hellman_group_exchange_sha256_key_exchange in kex.c has an integer overflow that could lead to an out-of-bounds write in the way packets are read from the server. 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. This is related to an _libssh2_check_length mistake, and is different from the various issues fixed in 1.8.1, such as CVE-2019-3855.

The weakness was shared 07/16/2019 (Website). The advisory is shared at lists.fedoraproject.org. The identification of this vulnerability is CVE-2019-13115 since 06/30/2019. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 1.9.0 eliminates this vulnerability.

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Productinfo

Name

• Libssh2

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8

Website

• Product: https://github.com/libssh2/libssh2/

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