Cisco Small Business Switches Secure Shell Certificate Authentication Bypass Vulnerability

published 2019-05-03 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-10416

cvss: 7.2; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.8%; EPSS 0.8% chance of exploitation in 30 days, percentile 58%
public exploits: 0; none known

A vulnerability in the Secure Shell (SSH) authentication process of Cisco Small Business Switches software could allow an attacker to bypass client-side certificate authentication and revert to password authentication. The vulnerability exists because OpenSSH mishandles the authentication process. An attacker could exploit this vulnerability by attempting to connect to the device via SSH. A successful exploit could allow the attacker to access the configuration as an administrative user if the default credentials are not changed. There are no workarounds available; however, if client-side certificate authentication is enabled, disable it and use strong password authentication. Client-side certificate authentication is disabled by default.

Patch / fix

fixed in 1

Cisco Cisco Small Business 200 Series Smart Switches 1.4.10.6, 2.5.0.78

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 23 mo ago (2024-11-20)

Exploit prediction

0.84% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	7.2	CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	7.2	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.5	AV:N/AC:L/Au:S/C:P/I:P/A:P

Affected products

Cisco Cisco Small Business 200 Series Smart Switches

Classification

Weakness

CWE-285 Improper Authorization
CWE-295 Improper Certificate Validation

References

tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-scbv
vendor-advisory

Sources

CVE List CVE-2019-1859
NVD CVE-2019-1859

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Summary