CVE-2026-73435 (GCVE-0-2026-73435)
Vulnerability from cvelistv5 – Published: 2026-09-16 09:19 – Updated: 2026-09-16 10:13
VLAI
EPSS
VEX
Title
Security Advisory 0171
Summary
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.
Severity
CWE
- CWE-345 - Insufficient Verification of Data Authenticity
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://www.arista.com/en/support/advisories-noti… | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Arista Networks | EOS |
Affected:
4.36.0F , ≤ 4.36.1F
(custom)
Affected: 4.35.0F , ≤ 4.35.5M (custom) Affected: 4.34.0F , ≤ 4.34.7M (custom) Affected: 4.33.0F , ≤ 4.33.9M (custom) Affected: 1.0.0 , < 4.33.0F (custom) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"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"
],
"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"
}
]
}
],
"configurations": [
{
"lang": "en",
"supportingMedia": [
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"type": "text/html",
"value": "\u003cp\u003eIn order to be vulnerable to CVE-2026-73435, all of the following conditions must be met:\u003c/p\u003e\u003col\u003e\u003cli\u003eThe vulnerable OSPFv2 instance must have at least two neighbors on the same interface.\u003c/li\u003e\u003cli\u003eThe interface is a broadcast interface.\u003c/li\u003e\u003cli\u003eOSPFv2 cryptographic authentication is configured.\u003c/li\u003e\u003c/ol\u003e\u003cp\u003eHere is an example showing a vulnerable OSPFv2 instance with a minimum of two neighbors on the same interface:\u003c/p\u003e\u003cpre\u003eswitch\u003eshow ip ospf neighbor\nNeighbor ID Instance VRF ... Interface\nX.X.X.X X ... ... \u0026lt;intf\u0026gt;\nX.X.X.X X ... ... \u0026lt;intf\u0026gt;\u003c/pre\u003e\u003cp\u003eHere is an example showing the vulnerable configuration of Network Type \u0026quot;Broadcast\u0026quot; and Message-digest authentication (cryptographic authentication) configured:\u003c/p\u003e\u003cpre\u003eswitch\u003eshow ip ospf interface\n\u0026lt;intf\u0026gt; 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 ...\u003c/pre\u003e\u003cp\u003eNote: Both \u0026quot;Message-digest authentication\u0026quot; (MD5) and \u0026quot;Message-digest sha\u0026lt;X\u0026gt; authentication\u0026quot; (SHA) are vulnerable.\u003c/p\u003e\u003cp\u003eTo check area-level authentication, reference the vulnerable interface area ID in \u0026quot;show ip ospf\u0026quot; output:\u003c/p\u003e\u003cpre\u003eswitch\u003eshow 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\u003c/pre\u003e\u003cp\u003eIf the area has \u0026quot;Simple\u0026quot; or \u0026quot;None\u0026quot; authentication, then at the area-level, the third prerequisite is unmet and the system would not be vulnerable to this particular issue.\u003c/p\u003e"
}
],
"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."
}
],
"descriptions": [
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"lang": "en",
"supportingMedia": [
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"type": "text/html",
"value": "\u003cp\u003eOn 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.\u003c/p\u003e\u003cp\u003eThese issues were discovered internally by Arista, and the company is not aware of any malicious uses of these issues in customer networks.\u003c/p\u003e"
}
],
"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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.2,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H",
"version": "3.1"
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"format": "CVSS",
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"lang": "en",
"value": "GENERAL"
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},
{
"cvssV4_0": {
"baseScore": 7,
"baseSeverity": "HIGH",
"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",
"version": "4.0"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-345",
"description": "CWE-345 Insufficient Verification of Data Authenticity",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-16T10:13:38.708Z",
"orgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
"shortName": "Arista"
},
"references": [
{
"name": "Security Advisory 0171",
"tags": [
"vendor-advisory"
],
"url": "https://www.arista.com/en/support/advisories-notices/security-advisory/24727-security-advisory-0171"
}
],
"solutions": [
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"lang": "en",
"supportingMedia": [
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"value": "\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003eCVE-2026-73435 has been fixed in the following releases:\u003c/p\u003e\u003cul\u003e\u003cli\u003e4.36.2F and later releases in the 4.36.x train\u003c/li\u003e\u003cli\u003e4.35.6M and later releases in the 4.35.x train\u003c/li\u003e\u003cli\u003e4.34.7.1M 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\u003cp\u003eA hotfix is available for the following releases: 4.36.1F, 4.35.5M, 4.34.7M, 4.33.9M.\u003cbr\u003eURL: https://www.arista.com/support/advisories-notices/sa-download/?sa171-SecurityAdvisory171_CVE-2026-73435.swix\u003cbr\u003eSWIX hash (SHA512): 4c4ff053d8165f347b45dfcafc2d20396e3eb00869b0088f3128be7f53b2a028b479fa8279849c800b5916ab9aaf8077718a68e3bf4277d55b44076650de0aa7\u003cbr\u003eNote: Installing/uninstalling the SWIX will cause the Ospf process to restart.\u003c/p\u003e"
}
],
"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."
}
],
"source": {
"advisory": "Security Advisory 0171",
"defects": [
"BUG 1843809"
],
"discovery": "INTERNAL"
},
"title": "Security Advisory 0171",
"workarounds": [
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"lang": "en",
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"value": "\u003cp\u003eNo mitigation is available for CVE-2026-73435.\u003c/p\u003e"
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"value": "No mitigation is available for CVE-2026-73435."
}
]
}
},
"cveMetadata": {
"assignerOrgId": "c8b34d1a-69ae-45c3-88fe-f3b3d44f39b7",
"assignerShortName": "Arista",
"cveId": "CVE-2026-73435",
"datePublished": "2026-09-16T09:19:47.285Z",
"dateReserved": "2026-08-12T16:39:35.976Z",
"dateUpdated": "2026-09-16T10:13:38.708Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-73435\",\"sourceIdentifier\":\"psirt@arista.com\",\"published\":\"2026-09-16T10:16:51.363\",\"lastModified\":\"2026-09-16T10:16:51.363\",\"vulnStatus\":\"Received\",\"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.\"}],\"affected\":[{\"source\":\"psirt@arista.com\",\"affectedData\":[{\"vendor\":\"Arista Networks\",\"product\":\"EOS\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"4.36.0F\",\"lessThanOrEqual\":\"4.36.1F\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.35.0F\",\"lessThanOrEqual\":\"4.35.5M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.34.0F\",\"lessThanOrEqual\":\"4.34.7M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"4.33.0F\",\"lessThanOrEqual\":\"4.33.9M\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"1.0.0\",\"lessThan\":\"4.33.0F\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"cvssData\":{\"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/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\":7.0,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"HIGH\",\"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:C/C:N/I:L/A:H\",\"baseScore\":8.2,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":4.7}]},\"weaknesses\":[{\"source\":\"psirt@arista.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-345\"}]}],\"references\":[{\"url\":\"https://www.arista.com/en/support/advisories-notices/security-advisory/24727-security-advisory-0171\",\"source\":\"psirt@arista.com\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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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.
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.
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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.
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