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CVE-2026-19655 (GCVE-0-2026-19655)

Vulnerability from cvelistv5 – Published: 2026-09-15 20:56 – Updated: 2026-09-15 20:56
VLAI
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
Summary
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.
CWE
  • CWE-20 - Improper Input Validation
References
Impacted products
Vendor Product Version CPE status
Arista Networks EOS Affected: 4.35.0 , ≤ 4.35.5M (custom)
Affected: 4.34.0 , ≤ 4.34.7.1M (custom)
Affected: 4.33.0 , ≤ 4.33.9M (custom)
guessed Create a notification for this product.
Date Public
2026-09-09 20:56
Show details on NVD website

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "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"
          ],
          "product": "EOS",
          "vendor": "Arista Networks",
          "versions": [
            {
              "changes": [
                {
                  "at": "4.35.6M",
                  "status": "unaffected"
                }
              ],
              "lessThanOrEqual": "4.35.5M",
              "status": "affected",
              "version": "4.35.0",
              "versionType": "custom"
            },
            {
              "changes": [
                {
                  "at": "4.34.8M",
                  "status": "unaffected"
                }
              ],
              "lessThanOrEqual": "4.34.7.1M",
              "status": "affected",
              "version": "4.34.0",
              "versionType": "custom"
            },
            {
              "changes": [
                {
                  "at": "4.33.10M",
                  "status": "unaffected"
                }
              ],
              "lessThanOrEqual": "4.33.9M",
              "status": "affected",
              "version": "4.33.0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eIn order to be vulnerable to CVE-2026-19655, any of the following conditions must be met:\u003c/p\u003e\u003cp\u003e1. Configure \"ip dhcp relay\" with the \"information option\" (Option 82) and at least one helper-address on an interface:\u003c/p\u003e\u003cpre\u003einterface Vlan100\n   ip helper-address 1.1.1.2\n   ip dhcp relay information option\u003c/pre\u003e\u003cp\u003e2. Configure \"ip dhcp snooping\" with the \"information option\":\u003c/p\u003e\u003cpre\u003eswitch#show running-config | grep snooping\nip dhcp snooping\nip dhcp snooping information option\nip dhcp snooping vlan 100\u003c/pre\u003e\u003cp\u003e3. The DHCP server uses match criteria based on the information option, configured with \"information option arista-switch\" commands:\u003c/p\u003e\u003cpre\u003edhcp 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\u003c/pre\u003e"
            }
          ],
          "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"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "This issue was discovered internally by Arista."
        }
      ],
      "datePublic": "2026-09-09T20:56:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eOn 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.\u003c/p\u003e"
            }
          ],
          "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."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-153",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-153 Input Data Manipulation"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "ADJACENT",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20 Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-15T20:56:46.678Z",
        "orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
        "shortName": "Arista"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24711-security-advisory-0155"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eThe recommended resolution is to upgrade to a remediated software version at your earliest convenience. CVE-2026-19655 has been fixed in the following releases:\u003c/p\u003e\u003cul\u003e\u003cli\u003e4.35.6M and later releases in the 4.35.x train\u003c/li\u003e\u003cli\u003e4.34.8M and later releases in the 4.34.x train\u003c/li\u003e\u003cli\u003e4.33.10M and later releases in the 4.33.x train\u003c/li\u003e\u003c/ul\u003e"
            }
          ],
          "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"
        }
      ],
      "source": {
        "advisory": "155",
        "defect": [
          "1770194"
        ],
        "discovery": "INTERNAL"
      },
      "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",
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eThere is no workaround known for this issue.\u003c/p\u003e"
            }
          ],
          "value": "There is no workaround known for this issue."
        }
      ],
      "x_generator": {
        "engine": "Vulnogram 1.0.5"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
    "assignerShortName": "Arista",
    "cveId": "CVE-2026-19655",
    "datePublished": "2026-09-15T20:56:46.678Z",
    "dateReserved": "2026-08-12T18:51:29.572Z",
    "dateUpdated": "2026-09-15T20:56:46.678Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-19655\",\"sourceIdentifier\":\"psirt@arista.com\",\"published\":\"2026-09-15T21:16:36.380\",\"lastModified\":\"2026-09-15T21:16:36.380\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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.\"}],\"affected\":[{\"source\":\"psirt@arista.com\",\"affectedData\":[{\"vendor\":\"Arista Networks\",\"product\":\"EOS\",\"defaultStatus\":\"unaffected\",\"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\":[{\"version\":\"4.35.0\",\"lessThanOrEqual\":\"4.35.5M\",\"versionType\":\"custom\",\"status\":\"affected\",\"changes\":[{\"at\":\"4.35.6M\",\"status\":\"unaffected\"}]},{\"version\":\"4.34.0\",\"lessThanOrEqual\":\"4.34.7.1M\",\"versionType\":\"custom\",\"status\":\"affected\",\"changes\":[{\"at\":\"4.34.8M\",\"status\":\"unaffected\"}]},{\"version\":\"4.33.0\",\"lessThanOrEqual\":\"4.33.9M\",\"versionType\":\"custom\",\"status\":\"affected\",\"changes\":[{\"at\":\"4.33.10M\",\"status\":\"unaffected\"}]}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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/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\",\"baseScore\":7.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":6.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-20\"}]}],\"references\":[{\"url\":\"https://www.arista.com/en/support/advisories-notices/security-advisory/24711-security-advisory-0155\",\"source\":\"psirt@arista.com\"}]}}"
  }
}



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