{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-73435", "assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "state": "PUBLISHED", "assignerShortName": "Arista", "dateReserved": "2026-08-12T16:39:35.976Z", "datePublished": "2026-09-16T09:19:47.285Z", "dateUpdated": "2026-09-16T10:13:38.708Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7", "shortName": "Arista", "dateUpdated": "2026-09-16T10:13:38.708Z"}, "title": "Security Advisory 0171", "descriptions": [{"lang": "en", "value": "On affected platforms running Arista EOS with Open Shortest Path First version 2 (OSPFv2) configured, a specially crafted OSPFv2 packet from an unauthenticated attacker on the same broadcast segment, with OSPFv2 authentication configured can cause adjacency flapping and packet loss. The disruption can affect routing across the broader OSPF domain.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>On affected platforms running Arista EOS with Open Shortest Path First version 2 (OSPFv2) configured, a specially crafted OSPFv2 packet from an unauthenticated attacker on the same broadcast segment, with OSPFv2 authentication configured can cause adjacency flapping and packet loss. The disruption can affect routing across the broader OSPF domain.</p><p>These issues were discovered internally by Arista, and the company is not aware of any malicious uses of these issues in customer networks.</p>"}]}], "affected": [{"vendor": "Arista Networks", "product": "EOS", "defaultStatus": "unaffected", "versions": [{"version": "4.36.0F", "lessThanOrEqual": "4.36.1F", "status": "affected", "versionType": "custom"}, {"version": "4.35.0F", "lessThanOrEqual": "4.35.5M", "status": "affected", "versionType": "custom"}, {"version": "4.34.0F", "lessThanOrEqual": "4.34.7M", "status": "affected", "versionType": "custom"}, {"version": "4.33.0F", "lessThanOrEqual": "4.33.9M", "status": "affected", "versionType": "custom"}, {"version": "1.0.0", "lessThan": "4.33.0F", "status": "affected", "versionType": "custom"}], "platforms": ["710 Series", "720D Series", "720XP/722XPM Series", "750X Series", "7010 Series", "7010X Series", "7020R/R4 Series", "7130 Series running EOS", "7150 Series", "7160 Series", "7170 Series", "7050X/X2/X3/X4 Series", "7060X/X2/X4/X5/X6 Series", "7250X 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"]}], "configurations": [{"lang": "en", "value": "In order to be vulnerable to CVE-2026-73435, all of the following conditions must be met:\n\n1. The vulnerable OSPFv2 instance must have at least two neighbors on the same interface.\n2. The interface is a broadcast interface.\n3. OSPFv2 cryptographic authentication is configured.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>In order to be vulnerable to CVE-2026-73435, all of the following conditions must be met:</p><ol><li>The vulnerable OSPFv2 instance must have at least two neighbors on the same interface.</li><li>The interface is a broadcast interface.</li><li>OSPFv2 cryptographic authentication is configured.</li></ol><p>Here is an example showing a vulnerable OSPFv2 instance with a minimum of two neighbors on the same interface:</p><pre>switch>show ip ospf neighbor\nNeighbor ID Instance VRF ... Interface\nX.X.X.X X ... ... &lt;intf&gt;\nX.X.X.X X ... ... &lt;intf&gt;</pre><p>Here is an example showing the vulnerable configuration of Network Type &quot;Broadcast&quot; and Message-digest authentication (cryptographic authentication) configured:</p><pre>switch>show ip ospf interface\n&lt;intf&gt; is up\n Interface Address X.X.X.X/X, instance X, VRF X, Area X.X.X.X\n Network Type Broadcast, Cost: X\n ...\n Message-digest authentication, using key id X\n ...</pre><p>Note: Both &quot;Message-digest authentication&quot; (MD5) and &quot;Message-digest sha&lt;X&gt; authentication&quot; (SHA) are vulnerable.</p><p>To check area-level authentication, reference the vulnerable interface area ID in &quot;show ip ospf&quot; output:</p><pre>switch>show ip ospf\nOSPF instance X with ID X.X.X.X VRF X\n...\nArea X.X.X.X\n Number of interface in this area is X\n It is a X area\n Traffic engineering is disabled\n Area has MD5 authentication</pre><p>If the area has &quot;Simple&quot; or &quot;None&quot; authentication, then at the area-level, the third prerequisite is unmet and the system would not be vulnerable to this particular issue.</p>"}]}], "workarounds": [{"lang": "en", "value": "No mitigation is available for CVE-2026-73435.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>No mitigation is available for CVE-2026-73435.</p>"}]}], "solutions": [{"lang": "en", "value": "The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below.\n\nCVE-2026-73435 has been fixed in the following releases:\n- 4.36.2F and later releases in the 4.36.x train\n- 4.35.6M and later releases in the 4.35.x train\n- 4.34.7.1M and later releases in the 4.34.x train\n- 4.33.10M and later releases in the 4.33.x train\n\nA hotfix is available for the following releases: 4.36.1F, 4.35.5M, 4.34.7M, 4.33.9M.\nURL: https://www.arista.com/support/advisories-notices/sa-download/?sa171-SecurityAdvisory171_CVE-2026-73435.swix\nSWIX hash (SHA512): 4c4ff053d8165f347b45dfcafc2d20396e3eb00869b0088f3128be7f53b2a028b479fa8279849c800b5916ab9aaf8077718a68e3bf4277d55b44076650de0aa7\nNote: Installing/uninstalling the SWIX will cause the Ospf process to restart.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>The recommended resolution is to upgrade to a remediated software version at your earliest convenience. Arista recommends customers move to the latest version of each release that contains all the fixes listed below.</p><p>CVE-2026-73435 has been fixed in the following releases:</p><ul><li>4.36.2F and later releases in the 4.36.x train</li><li>4.35.6M and later releases in the 4.35.x train</li><li>4.34.7.1M and later releases in the 4.34.x train</li><li>4.33.10M and later releases in the 4.33.x train</li></ul><p>A hotfix is available for the following releases: 4.36.1F, 4.35.5M, 4.34.7M, 4.33.9M.<br>URL: https://www.arista.com/support/advisories-notices/sa-download/?sa171-SecurityAdvisory171_CVE-2026-73435.swix<br>SWIX hash (SHA512): 4c4ff053d8165f347b45dfcafc2d20396e3eb00869b0088f3128be7f53b2a028b479fa8279849c800b5916ab9aaf8077718a68e3bf4277d55b44076650de0aa7<br>Note: Installing/uninstalling the SWIX will cause the Ospf process to restart.</p>"}]}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH"}}, {"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"version": "4.0", "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", "baseScore": 7, "baseSeverity": "HIGH"}}], "problemTypes": [{"descriptions": [{"type": "CWE", "lang": "en", "cweId": "CWE-345", "description": "CWE-345 Insufficient Verification of Data Authenticity"}]}], "references": [{"url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24727-security-advisory-0171", "name": "Security Advisory 0171", "tags": ["vendor-advisory"]}], "source": {"advisory": "Security Advisory 0171", "defects": ["BUG 1843809"], "discovery": "INTERNAL"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "EOS", "vendor": "Arista Networks", "versions": [{"lessThanOrEqual": "4.36.1F", "status": "affected", "version": "4.36.0F", "versionType": "custom"}, {"lessThanOrEqual": "4.35.5M", "status": "affected", "version": "4.35.0F", "versionType": "custom"}, {"lessThanOrEqual": "4.34.7M", "status": "affected", "version": "4.34.0F", "versionType": "custom"}, {"lessThanOrEqual": "4.33.9M", "status": "affected", "version": "4.33.0F", "versionType": "custom"}, {"lessThan": "4.33.0F", "status": "affected", "version": "1.0.0", "versionType": "custom"}]}], "source": "psirt@arista.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "On affected platforms running Arista EOS with Open Shortest Path First version 2 (OSPFv2) configured, a specially crafted OSPFv2 packet from an unauthenticated attacker on the same broadcast segment, with OSPFv2 authentication configured can cause adjacency flapping and packet loss. The disruption can affect routing across the broader OSPF domain."}], "id": "CVE-2026-73435", "lastModified": "2026-09-16T10:16:51.363", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 4.7, "source": "psirt@arista.com", "type": "Secondary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "ADJACENT", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.0, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "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/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", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "psirt@arista.com", "type": "Secondary"}]}, "published": "2026-09-16T10:16:51.363", "references": [{"source": "psirt@arista.com", "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24727-security-advisory-0171"}], "sourceIdentifier": "psirt@arista.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-345"}], "source": "psirt@arista.com", "type": "Secondary"}]}

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