CVE-2026-77190 (GCVE-0-2026-77190)
Vulnerability from cvelistv5
Published
2026-09-16 10:08
Modified
2026-09-16 13:26
Severity ?
6.5 (Medium) - CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.0 (Medium) - 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
6.0 (Medium) - 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
VLAI Severity ?
EPSS score ?
CWE
- CWE-20 - Improper Input Validation
Summary
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.
References
| URL | Tags | |
|---|---|---|
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Arista Networks | EOS |
Version: 4.36.0F < Version: 4.35.0F < Version: 4.34.2F < |
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"value": "\u003cp\u003eIn order to be vulnerable to CVE-2026-77190, the following conditions must both be met:\u003c/p\u003e\u003cp\u003e1. PIM Sparse Mode must be configured (IPv4 or IPv6). For example:\u003c/p\u003e\u003cpre\u003eswitch(config)# interface Ethernet1\nswitch(config-if-Et1)# pim ipv4 sparse-mode\n\nswitch# show agent Pimsm uptime\n Agent Name Restarts Uptime\n------------------ -------------- ----------------\nPimsm 1 2 days, 14:00:28\u003c/pre\u003e\u003cp\u003eor\u003c/p\u003e\u003cpre\u003eswitch(config)# interface Vlan2\nswitch(config-if-Vl2)# pim ipv6 sparse-mode\n\nswitch# show agent Pimsm6 uptime\n Agent Name Restarts Uptime\n------------------ -------------- ----------------\nPimsm6 3 2 days, 14:00:20\u003c/pre\u003e\u003cp\u003e2. MLAG must be configured and active:\u003c/p\u003e\u003cpre\u003eswitch(config)# mlag\nswitch(config-mlag)# local-interface vlan 4094\nswitch(config-mlag)# peer-address 10.0.0.2\nswitch(config-mlag)# peer-link port-channel 10\nswitch(config-mlag)# domain-id mlag1\n\nswitch# show mlag\nMLAG Configuration:\ndomain-id : mlag1\nlocal-interface : Vlan4094\npeer-address : 10.0.0.2\npeer-link : Port-Channel10\nMLAG Status:\nstate : Active\npeer-link status : Up\nlocal-int status : Up\nsystem-id : 00:11:22:01:03:01\u003c/pre\u003e"
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PIM Sparse Mode must be configured (IPv4 or IPv6). For example:\\n\\n switch(config)# interface Ethernet1\\n switch(config-if-Et1)# pim ipv4 sparse-mode\\n\\n switch# show agent Pimsm uptime\\n Agent Name Restarts Uptime\\n ------------------ -------------- ----------------\\n Pimsm 1 2 days, 14:00:28\\n\\nor\\n\\n switch(config)# interface Vlan2\\n switch(config-if-Vl2)# pim ipv6 sparse-mode\\n\\n switch# show agent Pimsm6 uptime\\n Agent Name Restarts Uptime\\n ------------------ -------------- ----------------\\n Pimsm6 3 2 days, 14:00:20\\n\\n2. 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For example:\u003c/p\u003e\u003cpre\u003eswitch(config)# interface Ethernet1\\nswitch(config-if-Et1)# pim ipv4 sparse-mode\\n\\nswitch# show agent Pimsm uptime\\n Agent Name Restarts Uptime\\n------------------ -------------- ----------------\\nPimsm 1 2 days, 14:00:28\u003c/pre\u003e\u003cp\u003eor\u003c/p\u003e\u003cpre\u003eswitch(config)# interface Vlan2\\nswitch(config-if-Vl2)# pim ipv6 sparse-mode\\n\\nswitch# show agent Pimsm6 uptime\\n Agent Name Restarts Uptime\\n------------------ -------------- ----------------\\nPimsm6 3 2 days, 14:00:20\u003c/pre\u003e\u003cp\u003e2. MLAG must be configured and active:\u003c/p\u003e\u003cpre\u003eswitch(config)# mlag\\nswitch(config-mlag)# local-interface vlan 4094\\nswitch(config-mlag)# peer-address 10.0.0.2\\nswitch(config-mlag)# peer-link port-channel 10\\nswitch(config-mlag)# domain-id mlag1\\n\\nswitch# show mlag\\nMLAG Configuration:\\ndomain-id : mlag1\\nlocal-interface : Vlan4094\\npeer-address : 10.0.0.2\\npeer-link : Port-Channel10\\nMLAG Status:\\nstate : Active\\npeer-link status : Up\\nlocal-int status : Up\\nsystem-id : 00:11:22:01:03:01\u003c/pre\u003e\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7\", \"shortName\": \"Arista\", \"dateUpdated\": \"2026-09-16T10:08:55.181Z\"}}}",
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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