Vulnerability-Lookup

GHSA-986V-7QW9-P5P6

Vulnerability from github – Published: 2026-09-15 21:33 – Updated: 2026-09-15 21:33

Details

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.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

7.1 (High)


                  
                    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

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JSON

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{
  "affected": [],
  "aliases": [
    "CVE-2026-19655"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-15T21:16:36Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-986v-7qw9-p5p6",
  "modified": "2026-09-15T21:33:03Z",
  "published": "2026-09-15T21:33:03Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19655"
    },
    {
      "type": "WEB",
      "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24711-security-advisory-0155"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ]
}

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

Vulnerability from cvelistv5 – Published: 2026-09-15 20:56 – Updated: 2026-09-15 20:56

Title

Summary

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

7.1 (High)


                        
                          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

CWE

CWE-20 - Improper Input Validation

Assigner

Arista mitre root

References

1 reference

URL	Tags
https://www.arista.com/en/support/advisories-noti…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
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)

Date Public

2026-09-09 20:56

Credits

This issue was discovered internally by Arista.

Show details on NVD website

JSON

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{
  "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"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.