{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-19655", "assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "state": "PUBLISHED", "assignerShortName": "Arista", "dateReserved": "2026-08-12T18:51:29.572Z", "datePublished": "2026-09-15T20:56:46.678Z", "dateUpdated": "2026-09-16T18:03:27.624Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "shortName": "Arista", "dateUpdated": "2026-09-15T20:56:46.678Z" }, "title": "On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay/snooping configured with the information option (Option 82), or with the DHCP server configured with match criteria based on the information option, an unauthent", "datePublic": "2026-09-09T20:56:00.000Z", "problemTypes": [ { "descriptions": [ { "lang": "en", "cweId": "CWE-20", "description": "CWE-20 Improper Input Validation", "type": "CWE" } ] } ], "impacts": [ { "capecId": "CAPEC-153", "descriptions": [ { "lang": "en", "value": "CAPEC-153 Input Data Manipulation" } ] } ], "affected": [ { "vendor": "Arista Networks", "product": "EOS", "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", "7700R4 Series", "AWE 5000 Series", "AWE 7200R Series", "CloudEOS", "cEOS-lab", "vEOS-lab", "CloudVision eXchange", "virtual or physical appliance" ], "versions": [ { "status": "affected", "version": "4.35.0", "lessThanOrEqual": "4.35.5M", "changes": [ { "at": "4.35.6M", "status": "unaffected" } ], "versionType": "custom" }, { "status": "affected", "version": "4.34.0", "lessThanOrEqual": "4.34.7.1M", "changes": [ { "at": "4.34.8M", "status": "unaffected" } ], "versionType": "custom" }, { "status": "affected", "version": "4.33.0", "lessThanOrEqual": "4.33.9M", "changes": [ { "at": "4.33.10M", "status": "unaffected" } ], "versionType": "custom" } ], "defaultStatus": "unaffected" } ], "descriptions": [ { "lang": "en", "value": "On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay/snooping configured with the information option (Option 82), or with the DHCP server configured with match criteria based on the information option, an unauthenticated attacker connected to a client-facing VLAN(s) where the relay is configured can send a specially crafted packet that causes the DHCP Relay service to restart.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay/snooping configured with the information option (Option 82), or with the DHCP server configured with match criteria based on the information option, an unauthenticated attacker connected to a client-facing VLAN(s) where the relay is configured can send a specially crafted packet that causes the DHCP Relay service to restart.

" } ] } ], "references": [ { "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24711-security-advisory-0155", "tags": [ "vendor-advisory" ] } ], "configurations": [ { "lang": "en", "value": "In order to be vulnerable to CVE-2026-19655, any of the following conditions must be met:\n\n\n\n1. Configure \"ip dhcp relay\" with the \"information option\" (Option 82) and at least one helper-address on an interface:\n\n\n\ninterface Vlan100\n ip helper-address 1.1.1.2\n ip dhcp relay information option\n\n\n\n2. Configure \"ip dhcp snooping\" with the \"information option\":\n\n\n\nswitch#show running-config | grep snooping\nip dhcp snooping\nip dhcp snooping information option\nip dhcp snooping vlan 100\n\n\n\n3. The DHCP server uses match criteria based on the information option, configured with \"information option arista-switch\" commands:\n\n\n\ndhcp server\n client class ipv4 definition name\n assignments\n private-option 224 always-send type string data \"data1\"\n !\n match\n information option arista-switch Ethernet55/1 vlan 100\n !\n subnet 1.0.0.0/24\n range 1.0.0.1 1.0.0.5\ninterface Vlan10\n dhcp server ipv4", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

In order to be vulnerable to CVE-2026-19655, any of the following conditions must be met:

1. Configure \"ip dhcp relay\" with the \"information option\" (Option 82) and at least one helper-address on an interface:

interface Vlan100\n   ip helper-address 1.1.1.2\n   ip dhcp relay information option

2. Configure \"ip dhcp snooping\" with the \"information option\":

switch#show running-config | grep snooping\nip dhcp snooping\nip dhcp snooping information option\nip dhcp snooping vlan 100

3. The DHCP server uses match criteria based on the information option, configured with \"information option arista-switch\" commands:

dhcp server\n   client class ipv4 definition name\n      assignments\n         private-option 224 always-send type string data \"data1\"\n      !\n      match\n         information option arista-switch Ethernet55/1 vlan 100\n   !\n   subnet 1.0.0.0/24\n      range 1.0.0.1 1.0.0.5\ninterface Vlan10\n   dhcp server ipv4
" } ] } ], "workarounds": [ { "lang": "en", "value": "There is no workaround known for this issue.", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

There is no workaround known for this issue.

" } ] } ], "solutions": [ { "lang": "en", "value": "The recommended resolution is to upgrade to a remediated software version at your earliest convenience. CVE-2026-19655 has been fixed in the following releases:\n\n * 4.35.6M and later releases in the 4.35.x train\n * 4.34.8M and later releases in the 4.34.x train\n * 4.33.10M and later releases in the 4.33.x train", "supportingMedia": [ { "type": "text/html", "base64": false, "value": "

The recommended resolution is to upgrade to a remediated software version at your earliest convenience. CVE-2026-19655 has been fixed in the following releases:

" } ] } ], "credits": [ { "lang": "en", "value": "This issue was discovered internally by Arista.", "type": "finder" } ], "source": { "defect": [ "1770194" ], "advisory": "155", "discovery": "INTERNAL" }, "x_generator": { "engine": "Vulnogram 1.0.5" }, "metrics": [ { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV3_1": { "version": "3.1", "attackVector": "ADJACENT_NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH", "baseSeverity": "MEDIUM", "baseScore": 6.5, "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H" } }, { "format": "CVSS", "scenarios": [ { "lang": "en", "value": "GENERAL" } ], "cvssV4_0": { "attackVector": "ADJACENT", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subAvailabilityImpact": "NONE", "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": 7.1, "vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N" } } ] }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-09-16T18:02:48.292435Z", "id": "CVE-2026-19655", "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": "2026-09-16T18:03:27.624Z" } } ] } }