CVE-2026-77190

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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector ADJACENT_NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://www.arista.com/en/support/advisories-notices/security-advisory/24733-security-advisory-0177

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-16 10:16

Updated : 2026-09-16 10:16

NVD link : CVE-2026-77190

Mitre link : CVE-2026-77190

CVE.ORG link : CVE-2026-77190

JSON object : View

Products Affected

No product.

CWE

CWE-20

Improper Input Validation

{"id": "CVE-2026-77190", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "psirt@arista.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "ADJACENT_NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "psirt@arista.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.0, "Automatable": "NOT_DEFINED", "attackVector": "ADJACENT", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "LOW", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "psirt@arista.com", "affectedData": [{"vendor": "Arista Networks", "product": "EOS", "versions": [{"status": "affected", "version": "4.36.0F", "versionType": "custom", "lessThanOrEqual": "4.36.1F"}, {"status": "affected", "version": "4.35.0F", "versionType": "custom", "lessThanOrEqual": "4.35.5M"}, {"status": "affected", "version": "4.34.2F", "versionType": "custom", "lessThanOrEqual": "4.34.7M"}], "platforms": ["710 Series", "720D Series", "720XP/722XPM Series", "750X Series", "7010TX Series", "7020R/R4 Series", "7130 Series running EOS", "7170 Series", "7050X3/X4 Series", "7060X/X2/X4/X5/X6 Series", "7260X/X3 Series", "7280R/R2/R3/R4 Series", "7300X/X3 Series", "7320X Series", "7358X4 Series", "7368X4 Series", "7388X5 Series", "7500R/R2/R3 Series", "7800R3/R4 Series", "cEOS-lab", "vEOS-lab"], "defaultStatus": "unaffected"}]}], "published": "2026-09-16T10:16:53.030", "references": [{"url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24733-security-advisory-0177", "source": "psirt@arista.com"}], "vulnStatus": "Received", "weaknesses": [{"type": "Secondary", "source": "psirt@arista.com", "description": [{"lang": "en", "value": "CWE-20"}]}], "descriptions": [{"lang": "en", "value": "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."}], "lastModified": "2026-09-16T10:16:53.030", "sourceIdentifier": "psirt@arista.com"}