CVE-2019-16905
CVSS v3
7.8
HIGH
EPSS Score
2.2 %
exploit probability, as of 2026-10-04
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
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.
Technical details
- Published
- 2019-10-09
Frequently asked questions
What is CVE-2019-16905?
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.
Is CVE-2019-16905 actively exploited?
Active exploitation of CVE-2019-16905 has not been confirmed. Its EPSS score was 2.2% on 2026-10-04, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2019-16905?
CVE-2019-16905 has a CVSS v3 base score of 7.8 (HIGH severity).
Is CVE-2019-16905 affecting your environment?
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