Vulnerability · Published Sep 16, 2026 · Assigned by Arista

CVE-2026-77190Security Advisory 0177

Medium 6.5

In plain English

A medium-severity improper input validation in EOS from Arista Networks. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities).

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.3%top 79.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

On affected platforms running Arista EOS, an unauthenticated attacker who is network-adjacent to the switch and able to connect to a device with PIM Sparse Mode and MLAG configured, can send malformed messages that cause the Pimsm agent to terminate unexpectedly. The Pimsm agent is automatically restarted, but repeated attacks can cause the agent to restart continuously, resulting in a sustained denial of service.

Affected products (as reported)

Vendor	Product	Versions
Arista Networks	EOS	4.36.0F – through 4.36.1F4.35.0F – through 4.35.5M4.34.2F – through 4.34.7M

Weakness: CWE-20 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Security Advisory 0177 vendor-advisory