On affected platforms running Arista EOS with password authentication configured, a specially crafted password can create orphan authentication sessions. Repeated exploitation of this issue can exhaust available authentication resources, resulting in legitimate users being unable to log in to the device.

This issue was discovered internally by Arista, and the company is not aware of any malicious exploitation of this vulnerability in customer networks.

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Advisories

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Fixes

Solution

The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below. For more information about upgrading see EOS User Manual: Upgrades and Downgrades. CVE-2026-19641 has been fixed in the following releases: * 4.36.1F and later releases in the 4.36.x train. * 4.35.6M and later releases in the 4.35.x train. * 4.34.8M and later releases in the 4.34.x train. * 4.33.9M and later releases in the 4.33.x train.


Workaround

The workaround is to disable password based authentication services, such as Telnet and SSH. NOTE: This workaround only works for local authentication. There is no workaround if the device requires password authentication via a remote method, e.g. Terminal Access Controller Access-Control System Plus (TACACS+), Remote Authentication Dial In User Service (RADIUS) or Lightweight Directory Access Protocol (LDAP). Use the following command to disable Telnet. switch(config)#management telnet switch(config-mgmt-telnet)#shutdown   On the client host, use the following command to generate SSH keys. client# ssh-keygen -t ecdsa -b 521 -f testkey   Copy the SSH public key to the device and add it to the local user. switch(config)#copy scp:<local_path_with_keys>/testkey.pub flash: switch(config)#username <user> sshkey file flash:testkey.pub   Add public-key as the first protocol for SSH authentication, keep keyboard-interactive as the second protocol for now. switch(config)#management ssh switch(config)#authentication protocol public-key keyboard-interactive   Once you have verified that the user can know login without a password from the client host, remove keyboard-interactive from SSH authentication protocol configuration. switch(config)#management ssh switch(config)#authentication protocol public-key   WARNING: Incorrect configuration may block logins. Make sure public-key authentication works before removing keyboard-interactive from the configuration. Instead of public key, certificate-based authentication can also be used as a workaround for local users. Please find more details about how to configure certificate-based authentication in the SSH Certificates User Guide https://www.arista.com/en/support/toi/eos-4-22-1f/14286-ssh-certificates .

History

Tue, 15 Sep 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 15 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Description On affected platforms running Arista EOS with password authentication configured, a specially crafted password can create orphan authentication sessions. Repeated exploitation of this issue can exhaust available authentication resources, resulting in legitimate users being unable to log in to the device. This issue was discovered internally by Arista, and the company is not aware of any malicious exploitation of this vulnerability in customer networks.
Title On affected platforms running Arista EOS with password authentication configured, a specially crafted password can create orphan authentication sessions. Repeated exploitation of this issue can exhaust available authentication resources, resulting in legit
Weaknesses CWE-116
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Arista

Published:

Updated: 2026-09-15T19:25:06.761Z

Reserved: 2026-08-12T16:48:22.864Z

Link: CVE-2026-19641

cve-icon Vulnrichment

Updated: 2026-09-15T19:25:00.835Z

cve-icon NVD

Status : Received

Published: 2026-09-15T19:17:17.387

Modified: 2026-09-15T20:17:11.070

Link: CVE-2026-19641

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses