{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-73446", "assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "state": "PUBLISHED", "assignerShortName": "Arista", "dateReserved": "2026-08-12T16:42:47.920Z", "datePublished": "2026-09-15T23:08:19.771Z", "dateUpdated": "2026-09-16T19:34:18.384Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "shortName": "Arista", "dateUpdated": "2026-09-15T23:08:19.771Z" }, "title": "Security Advisory 0160", "problemTypes": [ { "descriptions": [ { "lang": "en", "cweId": "CWE-696", "description": "CWE-696: Incorrect Behavior Order", "type": "CWE" } ] } ], "impacts": [ { "capecId": "CAPEC-272", "descriptions": [ { "lang": "en", "value": "CAPEC-272 Protocol Manipulation" } ] } ], "affected": [ { "vendor": "Arista Networks", "product": "EOS", "versions": [ { "status": "affected", "version": "4.36.0", "lessThanOrEqual": "4.36.1F", "versionType": "custom" }, { "status": "affected", "version": "4.35.0", "lessThanOrEqual": "4.35.5M", "versionType": "custom" }, { "status": "affected", "version": "4.34.0", "lessThanOrEqual": "4.34.7.1M", "versionType": "custom" }, { "status": "affected", "version": "4.33.0", "lessThanOrEqual": "4.33.9M", "versionType": "custom" }, { "status": "affected", "version": "4.32.0", "lessThan": "4.33.0F", "versionType": "custom" }, { "status": "affected", "version": "4.31.0", "lessThan": "4.32.0F", "versionType": "custom" } ], "defaultStatus": "unaffected" } ], "descriptions": [ { "lang": "en", "value": "On affected platforms running Arista EOS with IS-IS configured on a broadcast interface, an unauthenticated attacker can send a crafted IS-IS Hello Protocol Data Unit (PDU) that causes the device to tear down an established IS-IS adjacency. This may result in traffic disruption and loss of IP reachability for prefixes advertised through that adjacency.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

On affected platforms running Arista EOS with IS-IS configured on a broadcast interface, an unauthenticated attacker can send a crafted IS-IS Hello Protocol Data Unit (PDU) that causes the device to tear down an established IS-IS adjacency. This may result in traffic disruption and loss of IP reachability for prefixes advertised through that adjacency.

" } ] } ], "references": [ { "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24716-security-advisory-0160", "name": "Security Advisory 0160", "tags": [ "vendor-advisory" ] } ], "metrics": [ { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV3_1": { "version": "3.1", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "baseSeverity": "HIGH", "baseScore": 7.4, "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H" } }, { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV4_0": { "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "HIGH", "baseScore": 7, "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:H" } } ], "configurations": [ { "lang": "en", "value": "IS-IS must be enabled on a broadcast (LAN) interface AND there should be an active IS-IS adjacency on that interface:\n\n\n\nswitch(config-router-isis)#show active\nrouter isis 1\n   net 49.0001.1111.1111.1001.00\nswitch(config-if-Et1)#show active\ninterface Ethernet1\n   isis enable 1\n\n\n\nswitch#show isis interface detail\nIS-IS Instance: 1 VRF: default\n\n\n  Interface Ethernet1:\n    Index: 4 SNPA: 2:2:0:1:0:0\n    MTU: 1497 Type: broadcast\n    Supported address families: IPv4, IPv6\n    Area proxy boundary is disabled\n    BFD IPv4 is disabled\n    BFD IPv6 is disabled\n    Hello padding is enabled\n    Level 1:\n      Metric: 10, Number of adjacencies: 1\n      LAN-ID: 1111.1111.1001.04, Priority: 64\n      DIS: 1111.1111.1001, DIS priority: 64\n      Authentication mode: None\n      TI-LFA protection is disabled for IPv4\n      TI-LFA protection is disabled for IPv6\n    Adjacency 1111.1111.1002:\n      State: UP, Level: 1 Type: Level 1 IS\n      Advertised hold time: 9\n      Neighbor supported address families: IPv4, IPv6\n      Address family match: Enabled\n      SNPA: 2:2:0:2:0:0, Priority: 64\n      IPv4 interface address: 10.0.0.2\n      IPv6 interface address: fe80::2:ff:fe02:0\n      Area addresses: 49.0001\n\n\n\n\n\nIf IS-IS is not configured OR IS-IS is configured only on point-to-point interfaces, there is no exposure to this issue.\n\n\n\n\n\nswitch#show isis interface detail\nIS-IS Instance: 1 VRF: default\n \n  Interface Ethernet1:\n    Index: 4 SNPA: P2P\n    MTU: 1497 Type: point-to-point\n    Supported address families: IPv4, IPv6\n    Area proxy boundary is disabled\n    BFD IPv4 is disabled\n    BFD IPv6 is disabled\n    Hello padding is enabled\n    Local fast flooding is disabled\n    Level 1:\n      Metric: 10, Number of adjacencies: 1\n      Link-ID: 04\n      Authentication mode: None\n      TI-LFA protection is disabled for IPv4\n      TI-LFA protection is disabled for IPv6\n    Adjacency 1111.1111.1002:\n      State: UP, Level: 1 Type: Level 1 IS\n      Advertised hold time: 30\n      Neighbor supported address families: IPv4, IPv6\n      Address family match: Enabled\n      IPv4 interface address: 1.0.0.2\n      IPv6 interface address: fe80::2:ff:fe02:0\n      Area addresses: 49.0001\n      Peer fast flooding is disabled", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

IS-IS must be enabled on a broadcast (LAN) interface AND there should be an active IS-IS adjacency on that interface:

switch(config-router-isis)#show active\nrouter isis 1\n   net 49.0001.1111.1111.1001.00\nswitch(config-if-Et1)#show active\ninterface Ethernet1\n   isis enable 1

switch#show isis interface detail\nIS-IS Instance: 1 VRF: default\n
\n  Interface Ethernet1:\n    Index: 4 SNPA: 2:2:0:1:0:0\n    MTU: 1497 Type: broadcast\n    Supported address families: IPv4, IPv6\n    Area proxy boundary is disabled\n    BFD IPv4 is disabled\n    BFD IPv6 is disabled\n    Hello padding is enabled\n    Level 1:\n      Metric: 10, Number of adjacencies: 1\n      LAN-ID: 1111.1111.1001.04, Priority: 64\n      DIS: 1111.1111.1001, DIS priority: 64\n      Authentication mode: None\n      TI-LFA protection is disabled for IPv4\n      TI-LFA protection is disabled for IPv6\n    Adjacency 1111.1111.1002:\n      State: UP, Level: 1 Type: Level 1 IS\n      Advertised hold time: 9\n      Neighbor supported address families: IPv4, IPv6\n      Address family match: Enabled\n      SNPA: 2:2:0:2:0:0, Priority: 64\n      IPv4 interface address: 10.0.0.2\n      IPv6 interface address: fe80::2:ff:fe02:0\n      Area addresses: 49.0001

If IS-IS is not configured OR IS-IS is configured only on point-to-point interfaces, there is no exposure to this issue.

switch#show isis interface detail\nIS-IS Instance: 1 VRF: default\n \n  Interface Ethernet1:\n    Index: 4 SNPA: P2P\n    MTU: 1497 Type: point-to-point\n    Supported address families: IPv4, IPv6\n    Area proxy boundary is disabled\n    BFD IPv4 is disabled\n    BFD IPv6 is disabled\n    Hello padding is enabled\n    Local fast flooding is disabled\n    Level 1:\n      Metric: 10, Number of adjacencies: 1\n      Link-ID: 04\n      Authentication mode: None\n      TI-LFA protection is disabled for IPv4\n      TI-LFA protection is disabled for IPv6\n    Adjacency 1111.1111.1002:\n      State: UP, Level: 1 Type: Level 1 IS\n      Advertised hold time: 30\n      Neighbor supported address families: IPv4, IPv6\n      Address family match: Enabled\n      IPv4 interface address: 1.0.0.2\n      IPv6 interface address: fe80::2:ff:fe02:0\n      Area addresses: 49.0001\n      Peer fast flooding is disabled
" } ] } ], "workarounds": [ { "lang": "en", "value": "No workaround is available for this issue.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

No workaround is available for this issue.

" } ] } ], "solutions": [ { "lang": "en", "value": "The recommended resolution is to upgrade to a fixed software version.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

The recommended resolution is to upgrade to a fixed software version.

" } ] } ], "credits": [ { "lang": "en", "value": "This issue was discovered internally by Arista and the company is not aware of any malicious uses of these issues in customer networks.", "type": "finder" } ], "source": { "advisory": "0160", "discovery": "UNKNOWN", "defects": [ "BUG1840504" ] }, "x_generator": { "engine": "Vulnogram 1.0.5" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-09-16T19:34:09.117613Z", "id": "CVE-2026-73446", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-16T19:34:18.384Z" } } ] } }