CVE-2026-58050

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.

• libssh2 https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc TODO: check with upstream, only affecting libssh2 on Winddows?