Pre-Authentication Integer Overflow in OpenSSH XMSS Key Parsing Algorithm

CVE-2019-16905 · HIGH Severity

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

OpenSSH 7.7 through 7.9 and 8.x before 8.1, when compiled with an experimental key type, has a pre-authentication integer overflow if a client or server is configured to use a crafted XMSS key. This leads to memory corruption and local code execution because of an error in the XMSS key parsing algorithm. NOTE: the XMSS implementation is considered experimental in all released OpenSSH versions, and there is no supported way to enable it when building portable OpenSSH.

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