libssh2 up to 1.11.1 SSH integer overflow

Summaryinfo

A vulnerability was found in libssh2 up to 1.11.1. It has been rated as problematic. Affected by this issue is some unknown functionality of the component SSH Handler. The manipulation leads to integer overflow. This vulnerability is uniquely identified as CVE-2026-58050. The attack is possible to be carried out remotely. Moreover, an exploit is present.

Detailsinfo

A vulnerability was found in libssh2 up to 1.11.1. It has been rated as problematic. This issue affects an unknown function of the component SSH Handler. 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:

libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.

The weakness was disclosed by ashdfrkl. It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-58050 since 06/28/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are unknown but a public exploit is available.

The exploit is available at github.com. It is declared as proof-of-concept.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-39970). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• libssh2

Version

• 1.11.0
• 1.11.1

CPE 2.3info

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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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