What’s Vulnerable › Vulnerabilities

CVE-2026-58050: libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-28 · updated 2026-10-25
• Weakness: CWE-190

Description

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.

Affected products

• libssh2: through 1.11.1

References

• https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc
• https://github.com/libssh2/libssh2/blob/master/src/publickey.c
• https://www.vulncheck.com/advisories/libssh2-integer-overflow-in-publickey-subsystem-attribute-allocation

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